Science.gov

Sample records for south central alaska

  1. South Central Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Glacial silt along the Copper River in Alaska is picked up by the wind and carried out over the Gulf of Alaska. This true-color MODIS image from October 26, 2001, shows a large gray dust plume spreading out over the Gulf. West of the Copper River Delta, Cook Inlet is full of sediment.

  2. GIS coverages of the Castle Mountain Fault, south central Alaska

    USGS Publications Warehouse

    Labay, Keith A.; Haeussler, Peter J.

    2001-01-01

    The Castle Mountain fault is one of several major east-northeast-striking faults in southern Alaska, and it is the only fault with had historic seismicity and Holocene surface faulting. This report is a digital compilation of three maps along the Castle Mountain fault in south central Alaska. This compilation consists only of GIS coverages of the location of the fault, line attributes indicating the certainty of the fault location, and information about scarp height, where measured. The files are presented in ARC/INFO export file format and include metadata.

  3. Index of streamflow and water quality records to September 30, 1978, south-central Alaska

    USGS Publications Warehouse

    Still, Patsy J.

    1980-01-01

    This report, which is one of a series of reports for Alaska, lists stations in south-central Alaska at which streamflow and water quality data have been collected by the U.S. Geological Survey. Included are a hydrologic subregion map of south-central Alaska and a table listing the types of data collected and periods of record. (USGS)

  4. Emsian (late Early Devonian) sponges from west-central and south-central Alaska

    USGS Publications Warehouse

    Rigby, J.K.; Blodgett, R.B.; Anderson, N.K.

    2009-01-01

    Relatively common specimens of the hypercalcified agelasiid sponge Hormospongia labyrinthica Rigby and Blodgett, 1983 and specimens of associated species of Hormospongia have been previously reported from Emsian and Eifelian stratigraphic units at several localities in south-central and southeastern Alaska (Rigby and Blodgett, 1983). Those sponges were first described from the type section of the Eifelian Cheeneetnuk Limestone in the McGrath A-5 quadrangle. Since then several additional specimens of Hormospongia labyrinthica have also been collected from a new locality in the Talkeetna C-6 quadrangle in southcentral Alaska (Figs. 1, 2.1), and are documented here.

  5. Geologic framework and petroleum systems of Cook Inlet basin, south-central Alaska

    USGS Publications Warehouse

    LePain, D.L.; Stanley, R.G.; Helmold, K.P.; Shellenbaum, D.P.

    2013-01-01

    This report provides a comprehensive overview of the stratigraphy, structure, tectonics, and petroleum systems of the Cook Inlet basin, an important oil- and gas-producing region in south-central Alaska.

  6. Seismicity and plate tectonics in south central Alaska

    NASA Technical Reports Server (NTRS)

    Van Wormer, J. D.; Davies, J.; Gedney, L.

    1974-01-01

    Hypocenter distribution shows that the Benioff zone associated with the Aleutian arc terminates in interior Alaska some 75 km north of the Denali fault. There appears to be a break in the subducting Pacific plate in the Yentna River-Prince William Sound area which separates two seismically independent blocks, similar to the segmented structure reported for the central Aleutian arc.

  7. 40 CFR 81.247 - South Central Alaska Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false South Central Alaska Intrastate Air Quality Control Region. 81.247 Section 81.247 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... portions of the 1956 Election Districts 7-17, inclusive, and Election District 24 as described in...

  8. Tephrochronologic Dating and Correlation of Historic and Prehistoric Tsunami Deposits in South-Central Alaska

    NASA Astrophysics Data System (ADS)

    Beget, J. E.; Combellick, R. A.; Addison, J.

    2007-12-01

    Volcanic Ash deposits can be used to identify, date and correlate tsunami deposits in the Cook Inlet and Prince William Sound areas of south-central Alaska. The 1964 Good Friday Earthquake (M9.2) produced a major regional tsunami that affected the entire coast of south-central Alaska, and coeval submarine landslides in Prince William Sound generated local tsunamis more than 30 m high. The 1964 tsunami deposits on Augustine Island in Cook Inlet are partly buried by tephras and pyroclastic flows from recent eruptions and record an 8-m-high wave. Tsunami deposits recording a volcanic tsunami produced by an eruption at Augustine Volcano in 1883 indicate initial wave heights of more than 18 m, and are overlain by coeval 1883 tephra and also Katmai 1912 tephra at multiple sites on Augustine Island, as well as at Nanwalek and Homer 80-100 km to the north. Newly discovered tsunami deposits recording the penultimate great earthquake on the subduction zone beneath south- central Alaska are dated to ca. 950 yr BP near Valdez. The tsunami deposits are overlain by a mafic tephra from the Wrangell area erupted ca. 750 yr BP. The tephra and new dates on the tsunami deposit help refine the age of the late major earthquake on the subduction zone beneath south-central Alaska, as there is wide range of radiocarbon dates associated with broadly coeval episodes of local subsidence identified at sites in Prince William Sound and Cook Inlet. A regionally extensive Augustine tephra erupted ca. 800 yr BP occurs in sediments deposited after the subsidence at several sites around Cook Inlet, and further helps refine the age of the penultimate great earthquake in south-central Alaska. An older tsunami deposit located near Homer is dated to ca. 3400 yr BP and occurs above tephra from Redoubt Volcano, and records an older subduction zone earthquake. A still older tsunami deposit dated to 3600 yr BP directly underlies the Redoubt tephra, and may have been generated by a huge eruption at Redoubt

  9. A slow slip event in the south central Alaska Subduction Zone and related seismicity anomaly

    NASA Astrophysics Data System (ADS)

    Wei, Meng; McGuire, Jeffrey J.; Richardson, Eliza

    2012-08-01

    We detected a slow slip event in the south central Alaska Subduction Zone by analyzing continuous GPS data from the Plate Boundary Observatory (PBO) network. The slow slip event started in early 2010 at a depth of 35 km beneath the Cook Inlet, near the down-dip end of the locked zone, and is ongoing as of November 2011 with an accumulated magnitude of Mw 6.9. Analysis of the earthquake catalog in the same area using the stochastic Epidemic Type Aftershock Sequence model (ETAS) shows a small but detectable seismicity increase during the slow slip event. We also find a change in seismicity rate around 1998, that may suggest an earlier slow slip event in the same region. Slow slip events in Alaska appear more widespread than previously thought but have remained undetected due to their long durations, the time intervals between them, and the limited time records from the continuous GPS.

  10. Geologic map of the Gulkana B-1 quadrangle, south-central Alaska

    SciTech Connect

    Richter, D.H.; Ratte, J.C.; Schmoll, H.R.; Leeman, W.P.; Smith, J.G.; Yehle, L.A.

    1989-01-01

    The quadrangle includes the Capital Mountain Volcano and the northern part of Mount Sanford Volcano in the Wrangell Mountains of south-central Alaska. The Capital Mountain volcano is a relatively small, andesitic shield volcano of Pleistocene age, which contains a 4-km-diameter summit caldera and a spectacular post-caldera radial dike swam. Lava flows from the younger Pleistocene Mount Sanford Volcano overlap the south side of the Capital Mountain Volcano. Copper-stained fractures in basaltic andesite related to a dike-filled rift of the North Sanford eruptive center are the only sign of mineralization in the quadrangle. Rock glaciers, deposits of Holocene and Pleistocene valley glaciers and Pleistocene Copper River basin glaciers mantle much of the volcanic bedrock below elevations of 5,500 ft.

  11. Climate variability and spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska.

    PubMed

    Sherriff, Rosemary L; Berg, Edward E; Miller, Amy E

    2011-07-01

    We used tree ring data (AD 1601-2007) to examine the occurrence of and climatic influences on spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska and found evidence of regional-scale outbreaks dating from the mid-1700s, related to climate variability at multiple temporal scales. Over interannual time scales (approximately 1-3 years), El Niño years, combined with severe late-summer drought, appeared to contribute significantly to spruce beetle outbreaks in the study area. Over multidecadal time scales (up to approximately 40 years), cool-phase Pacific Decadal Oscillation (PDO) conditions tended to precede beetle outbreaks, regardless of the phase of El Niño-Southern Oscillation (ENSO). All sites showed low-severity disturbances attributed to spruce beetle damage, most notably during the 1810s. During other major periods of disturbance (i.e., 1870s, 1910s, 1970s), the effects of spruce beetle outbreaks were of moderate or higher severity. The highly synchronized timing of spruce beetle outbreaks at interannual to multidecadal scales, and particularly the association between cool-phase PDO conditions and beetle disturbance, suggests that climate (i.e., temperature, precipitation) is a primary driver of outbreaks in the study area. Our disturbance chronologies (mid-1700s to present) suggest that recent irruptions (1990s to present) in south-central and southwest Alaska are within the historical geographic range, but that outbreaks since the 1990s show greater spatiotemporal synchrony (i.e., more sites record high-severity infestations) than at any other time in the past approximatly 250 years. PMID:21870620

  12. A Century of Retreat at Portage Glacier, South-Central Alaska

    USGS Publications Warehouse

    Kennedy, Ben W.; Trabant, Dennis C.; Mayo, Lawrence R.

    2006-01-01

    Introduction: The Portage Glacier, in south-central Alaska, is viewed by thousands of visitors annually who come to the U.S. Forest Service Begich, Boggs Visitor Center located on the road system between Anchorage and Whittier, Alaska. During the past century, the terminus of the glacier has retreated nearly 5 kilometers to its present location (fig. 1). Like other glaciers that terminate in water, such as Columbia Glacier near Valdez or Mendenhall Glacier near Juneau, Portage Glacier has experienced accelerated retreats in recent decades that likely were initially triggered by climate change begun at the end of the Little Ice Age in the mid-1800s and subsequently controlled in recent history primarily by calving of the glacier terminus. Photographic records of the terminus covering 1914 until present day track the patterns of retreat. These data, coupled with USGS climate information collected from the southern end of the ice field, provide insight to the patterns of retreat that might be observed in the future.

  13. Measurement and Modeling of Cryosphere-Geosphere Interactions in South Central Alaska

    NASA Astrophysics Data System (ADS)

    Sauber, J. M.; Han, S. C.; Luthcke, S. B.; Ruppert, N. A.; Bruhn, R. L.

    2014-12-01

    In south central Alaska large cryosphere fluctuations occur on a variety of temporal and spatial scales in a region of upper crustal faulting and folding associated with collision and accretion of the Yakutat terrane. Over the last decade (2002-present) the Gravity Recovery and Climate Experiment (GRACE) gravity measurements from southern Alaska indicate region-specific trends of annual mass loss and large variable seasonal mass fluctuations. Unraveling the various geophysical signals within GRACE and continuous GPS data, as well as earlier campaign GPS data, has required acquiring geodetic constraints on changes in the cryosphere from satellite, aircraft, and in situ data. At broad spatial scales, short-term atmospheric loading corrections are important as well. On a more local scale, we use snow accumulation profiles from Larson's GPS reflectometry, SNOTEL sites, and MODIS derived melt onset/refreeze timing to estimate the magnitude and timing of seasonal cryosphere loading and unloading. The regional GRACE trends need to be corrected for the rheological response to century time-scale ice mass loss as well. Our numerical modeling of the solid Earth response to cryosphere changes and earthquakes includes use of simple elastic models, regional finite element modeling with PyLith and a global normal model approach. For instance, our calculations predict the region specific GRACE trends due to ongoing mass change associated with viscoelastic relaxation following the 1964 and other earthquakes.

  14. Stratigraphic and compositional complexities of the late Quaternary Lethe tephra in South-central Alaska

    USGS Publications Warehouse

    Riehle, J.R.; Ager, T.A.; Reger, R.D.; Pinney, D.S.; Kaufman, D.S.

    2008-01-01

    Recently discovered Lethe tephra has been proposed as a latest Pleistocene marker bed in Bristol Bay lowland NE to the Cook Inlet region, Alaska, on the basis of correlations involving a single "Lethe average" glass composition. Type deposits in the Valley of Ten Thousand Smokes, however, are chemically heterogeneous-individual lapilli as well as aggregate ash deposits have glass compositions that range from the average mode to much higher SiO2 and K2O. Moreover, a lake-sediment core from the Cook Inlet region contains one ash deposit similar to "Lethe average" and other, closely underlying deposits that resemble a mixture of the average mode and high-Si high-K mode of proximal deposits. Synthesis of previously published radiocarbon ages indicates a major eruption mainly of "Lethe average" mode about 13,000 14C yr BP. As many as six deposits in the Cook Inlet region-five chiefly "Lethe average" mode-range from about 13,000 to 15-16,000 14C yr BP, and an early Holocene deposit in the Bristol Bay lowland extends the minimum age range of Lethe tephra throughout this region to 8000 14C yr BP. Because of the appearance of "Lethe average" composition in multiple deposits spanning thousands of years, we urge caution when using a Lethe-like composition as a basis for inferring a latest Pleistocene age of a tephra deposit in south-central Alaska. Linear variation plots suggest that magma mixing caused the Lethe heterogeneity; multiple magmas were involved as well in other large pyroclastic eruptions such as Katmai (Alaska) and Rotorua (New Zealand). Lethe is an example of a heterogeneous tephra that may be better compared with other tephras by use of plots of individual analytical points rather than by calculating similarity coefficients based on edited data. ?? 2006 Elsevier Ltd and INQUA.

  15. Three-dimensional numerical models of flat slab subduction and the Denali fault driving deformation in south-central Alaska

    NASA Astrophysics Data System (ADS)

    Jadamec, Margarete A.; Billen, Magali I.; Roeske, Sarah M.

    2013-08-01

    Early theories of plate tectonics assumed plates were rigid with deformation limited to within a few tens of kilometers of the plate boundary. However, observations indicate most continental plates defy such rigid behavior with deformation extending over 1000 kilometers inboard. We construct three-dimensional (3D) numerical models of the boundary between the Pacific and North American plates in Alaska to investigate the relative controls of flat slab subduction, continental scale faulting, and a non-linear rheology on deformation in the overriding plate. The models incorporate a realistic slab shape based on seismicity and seismic tomography and a variable thermal structure for both the subducting and overriding plates based on geologic and geophysical observables. The inclusion of the Denali fault in the models allows for the portion of south-central Alaska between the Denali fault and the trench to partially decouple from the rest of North America, forming an independently moving region that correlates to what has been described from geologic and geodetic studies as the Wrangell block. The motion of the Wrangell block tracks the motion of the flat slab in the subsurface indicating the subducting plate is driving the motion of the Wrangell block. Models using a composite (Newtonian and non-Newtonian) viscosity predict compressional motion along the northern bend in the Denali fault, consistent with thermochronologic data that show significant late Neogene exhumation in the central Alaska Range, including at Mt. McKinley, the tallest mountain in North America. These 3D numerical models of the Pacific-North American margin in Alaska show the subducting slab is the main driver of overriding plate deformation in south-central Alaska and combined with the Denali fault can reproduce several first order tectonic features of the region including the motion of the Wrangell block, uplift in the central Alaska Range, subsidence in the Cook Inlet-Susitna Basins, and upwelling

  16. Shrubline but not treeline advance matches climate velocity in montane ecosystems of south-central Alaska.

    PubMed

    Dial, Roman J; Scott Smeltz, T; Sullivan, Patrick F; Rinas, Christina L; Timm, Katriina; Geck, Jason E; Carl Tobin, S; Golden, Trevor S; Berg, Edward C

    2016-05-01

    Tall shrubs and trees are advancing into many tundra and wetland ecosystems but at a rate that often falls short of that predicted due to climate change. For forest, tall shrub, and tundra ecosystems in two pristine mountain ranges of Alaska, we apply a Bayesian, error-propagated calculation of expected elevational rise (climate velocity), observed rise (biotic velocity), and their difference (biotic inertia). We show a sensitive dependence of climate velocity on lapse rate and derive biotic velocity as a rigid elevational shift. Ecosystem presence identified from recent and historic orthophotos ~50 years apart was regressed on elevation. Biotic velocity was estimated as the difference between critical point elevations of recent and historic logistic fits divided by time between imagery. For both mountain ranges, the 95% highest posterior density of climate velocity enclosed the posterior distributions of all biotic velocities. In the Kenai Mountains, mean tall shrub and climate velocities were both 2.8 m y(-1) . In the better sampled Chugach Mountains, mean tundra retreat was 1.2 m y(-1) and climate velocity 1.3 m y(-1) . In each mountain range, the posterior mode of tall woody vegetation velocity (the complement of tundra) matched climate velocity better than either forest or tall shrub alone, suggesting competitive compensation can be important. Forest velocity was consistently low at 0.1-1.1 m y(-1) , indicating treeline is advancing slowly. We hypothesize that the high biotic inertia of forest ecosystems in south-central Alaska may be due to competition with tall shrubs and/or more complex climate controls on the elevational limits of trees than tall shrubs. Among tall shrubs, those that disperse farthest had lowest inertia. Finally, the rapid upward advance of woody vegetation may be contributing to regional declines in Dall's sheep (Ovis dalli), a poorly dispersing alpine specialist herbivore with substantial biotic inertia due to dispersal

  17. Assessment of unconvential (tight) gas resources in Upper Cook Inlet Basin, South-central Alaska

    USGS Publications Warehouse

    Schenk, Christopher J.; Nelson, Philip H.; Klett, Timothy R.; Le, Phuong A.; Anderson, Christopher P.

    2015-01-01

    A geologic model was developed for the assessment of potential Mesozoic tight-gas resources in the deep, central part of upper Cook Inlet Basin, south-central Alaska. The basic premise of the geologic model is that organic-bearing marine shales of the Middle Jurassic Tuxedni Group achieved adequate thermal maturity for oil and gas generation in the central part of the basin largely due to several kilometers of Paleogene and Neogene burial. In this model, hydrocarbons generated in Tuxedni source rocks resulted in overpressure, causing fracturing and local migration of oil and possibly gas into low-permeability sandstone and siltstone reservoirs in the Jurassic Tuxedni Group and Chinitna and Naknek Formations. Oil that was generated either remained in the source rock and subsequently was cracked to gas which then migrated into low-permeability reservoirs, or oil initially migrated into adjacent low-permeability reservoirs, where it subsequently cracked to gas as adequate thermal maturation was reached in the central part of the basin. Geologic uncertainty exists on the (1) presence of adequate marine source rocks, (2) degree and timing of thermal maturation, generation, and expulsion, (3) migration of hydrocarbons into low-permeability reservoirs, and (4) preservation of this petroleum system. Given these uncertainties and using known U.S. tight gas reservoirs as geologic and production analogs, a mean volume of 0.64 trillion cubic feet of gas was assessed in the basin-center tight-gas system that is postulated to exist in Mesozoic rocks of the upper Cook Inlet Basin. This assessment of Mesozoic basin-center tight gas does not include potential gas accumulations in Cenozoic low-permeability reservoirs.

  18. Assessment of undiscovered oil and gas resources of the Cook Inlet region, south-central Alaska, 2011

    USGS Publications Warehouse

    Stanley, Richard G.; Charpentier, Ronald R.; Cook, Troy A.; Houseknecht, David W.; Klett, Timothy R.; Lewis, Kristen A.; Lillis, Paul G.; Nelson, Philip H.; Phillips, Jeffrey D.; Pollastro, Richard M.; Potter, Christopher J.; Rouse, William A.; Saltus, Richard W.; Schenk, Christopher J.; Shah, Anjana K.; Valin, Zenon C.

    2011-01-01

    The U.S. Geological Survey (USGS) recently completed a new assessment of undiscovered, technically recoverable oil and gas resources in the Cook Inlet region of south-central Alaska. Using a geology-based assessment methodology, the USGS estimates that mean undiscovered volumes of nearly 600 million barrels of oil, about 19 trillion cubic feet of natural gas, and 46 million barrels of natural gas liquids remain to be found in this area.

  19. Coalbed methane, Cook Inlet, south-central Alaska: A potential giant gas resource

    USGS Publications Warehouse

    Montgomery, S.L.; Barker, C.E.

    2003-01-01

    Cook Inlet Basin of south-central Alaska is a forearc basin containing voluminous Tertiary coal deposits with sufficient methane content to suggest a major coalbed gas resource. Coals ranging in thickness from 2 to 50 ft (0.6 to 15 m) and in gas content from 50 to 250 scf/ton (1.6 to 7.8 cm2/g) occur in Miocene-Oligocene fluvial deposits of the Kenai Group. These coals have been identified as the probable source of more than 8 tcf gas that has been produced from conventional sandstone reservoirs in the basin. Cook Inlet coals can be divided into two main groups: (1) those of bituminous rank in the Tyonek Formation that contain mainly thermogenic methane and are confined to the northeastern part of the basin (Matanuska Valley) and to deep levels elsewhere; and (2) subbituminous coals at shallow depths (<5000 ft [1524 m]) in the Tyonek and overlying Beluga formations, which contain mainly biogenic methane and cover most of the central and southern basin. Based on core and corrected cuttings-desorption analyses, gas contents average 230 scf/ton (7.2 cm2/g) for bituminous coals and 80 scf/ton (2.5 cm2/g) for subbituminous coals. Isotherms constructed for samples of both coal ranks suggest that bituminous coals are saturated with respect to methane, whereas subbituminous coals at shallow depths along the eroded west-central basin margin are locally unsaturated. A preliminary estimate of 140 tcf gas in place is derived for the basin.

  20. Breeding ecology of Wandering Tattlers Tringa incana: a study from south-central Alaska

    USGS Publications Warehouse

    Gill, Robert; Tomkovich, Pavel S.; Dementyev, Maksim N.

    2015-01-01

    Montane-nesting shorebirds are arguably the least studied of the Charadriiformes, owing in part to the remoteness of their breeding areas, low nesting densities, and specialized behaviors. We studied a marked population of the Wandering Tattler Tringa incana, during a three-year period (1997–1999) on nesting grounds in south-central Alaska. Two aspects of our results stand out. First is the previously undescribed preference for tattlers to nest several kilometers removed from pre-nesting feeding areas, mostly in association with both small (kettle) lakes and running water (near small distributaries of major drainages). Second is the apparent use of the study area by cohorts of birds of different breeding status, including (1) local breeders, which defended pre-breeding foraging areas, (2) local non-breeding birds, which remained on the area but were not territorial, and (3) transients that were captured later in the season, but not seen again on the area during the season of capture. We also found that (1) birds tended to nest in clusters despite what appeared to be the ample availability of nesting habitat, (2) they employed an inconspicuous’ nesting strategy whereby neither member of a pair betrayed its presence on the nesting area, and (3) females departed the area during early chick-rearing, leaving males to tend broods.

  1. Seismicity and stress in the vicinity of Mount Spurr volcano, south central Alaska

    NASA Astrophysics Data System (ADS)

    Jolly, Arthur D.; Page, Robert A.; Power, John A.

    1994-08-01

    Focal mechanism solutions and hypocenters for earthquakes near Mount Spurr volcano in south central Alaska reveal spatial perturbations in the regional stress field and in the maximum depth of seismicity. At the volcano, practically all the shocks during the dormant decade 1981-1991 have depths shallower than 5 km and are characterized by nearly pure normal slip. In contrast, earthquakes located outboard of the volcano concentrate in the depth range 3-18 km and exhibit predominantly strike slip, oblique reverse slip, or reverse slip. The regional stress field is characterized by subhorizontal maximum principal stress directed N 30 deg W, concordant with the direction of convergence between the North American and Pacific plates, whereas the maximum principal stress is probably more nearly vertical beneath the volcano. We suggest that the shoaling of seismicity beneath the volcano reflects localized elevation of the depth to the midcrustal transition from brittle failure to plastic flow. We attribute this localized elevation to relict magmatic heat associated with past volcanic eruptions. The available data are not sufficient to determine the cause of the suggested rotation of the maximum principal stress axis beneath the volcano; possible mechanisms include an increase in the vertical stress from the weight of the Mount Spurr massif and a decrease in the maximum horizontal stress associated with doming of the shallow crust from magmatic processes.

  2. Estuarine environments as rearing habitats for juvenile Coho Salmon in contrasting south-central Alaska watersheds

    USGS Publications Warehouse

    Hoem Neher, Tammy D.; Rosenberger, Amanda E.; Zimmerman, Christian E.; Walker, Coowe M.; Baird, Steven J.

    2013-01-01

    For Pacific salmon, estuaries are typically considered transitional staging areas between freshwater and marine environments, but their potential as rearing habitat has only recently been recognized. The objectives of this study were two-fold: (1) to determine if Coho Salmon Oncorhynchus kisutch were rearing in estuarine habitats, and (2) to characterize and compare the body length, age, condition, and duration and timing of estuarine occupancy of juvenile Coho Salmon between the two contrasting estuaries. We examined use of estuary habitats with analysis of microchemistry and microstructure of sagittal otoliths in two watersheds of south-central Alaska. Juvenile Coho Salmon were classified as estuary residents or nonresidents (recent estuary immigrants) based on otolith Sr : Ca ratios and counts of daily growth increments on otoliths. The estuaries differed in water source (glacial versus snowmelt hydrographs) and in relative estuarine and watershed area. Juvenile Coho Salmon with evidence of estuary rearing were greater in body length and condition than individuals lacking evidence of estuarine rearing. Coho Salmon captured in the glacial estuary had greater variability in body length and condition, and younger age-classes predominated the catch compared with the nearby snowmelt-fed, smaller estuary. Estuary-rearing fish in the glacial estuary arrived later and remained longer (39 versus 24 d of summer growth) during the summer than did fish using the snowmelt estuary. Finally, we observed definitive patterns of overwintering in estuarine and near shore environments in both estuaries. Evidence of estuary rearing and overwintering with differences in fish traits among contrasting estuary types refute the notion that estuaries function as only staging or transitional habitats in the early life history of Coho Salmon.

  3. Diverging Histories of the Liberty Creek and Iceberg Lake Blueschist Bodies, south central Alaska

    NASA Astrophysics Data System (ADS)

    Day, E. M.; Pavlis, T. L.; Amato, J. M.

    2011-12-01

    New studies of the Liberty Creek and Iceberg Lake blueschist bodies of south central Alaska indicate that despite structural similarities, these blueschist bodies are derived from a different protolith and were metamorphosed to blueschist facies at distinctly different times. Both blueschists are located just south of the Border Ranges Fault (BRF) within outcrop belts of the McHugh Complex, a low-grade mélange assemblage that is now known from detrital zircon studies to consist of two distinct assemblages: a Jurassic to Earliest Cretaceous assemblage and a Late Cretaceous assemblage. The BRF is a megathrust system that represents the Late Triassic-Early Jurassic initiation of southern Alaskan subduction. Large scale (1:24,000) mapping revealed similar fabric overprint histories, epitomized by a previously undescribed youngest vertical N-S trending crenulation cleavage in both blueschist bodies which implies a structural correlation despite their separation of ~100 kilometers along strike. Despite structural similarities detrital zircon studies show that the Liberty Creek and Iceberg Lake blueschists do not have a similar maximum age of deposition. Thirteen samples from the Iceberg Lake blueschist were processed, none of which produced detrital zircons. Samples from the McHugh Complex greenschists that surround the Iceberg Lake blueschist produced numerous zircons indicating a Late Jurassic (~160 Ma) maximum age of deposition. Three out of sixteen samples from the Liberty creek blueschist produced detrital zircons indicating maximum depositional ages ranging from Late Jurassic (~160.1 Ma, n=64 grains; ~152.25 Ma, n=68 grains) to Early Cretaceous (~137.1 Ma, n=95 grains). The Late Jurassic dates are consistent with maximum depositional ages determined by Amato and Pavlis (2010) for McHugh Complex rocks along Turnagain Arm near Anchorage, AK. Sisson and Onstott (1986) reported a metamorphic cooling age of 185 Ma for the Iceberg Lake blueschist, thus, although no

  4. Non-volcanic Tremor Triggered by Teleseismic Surface Waves in South-Central Alaska

    NASA Astrophysics Data System (ADS)

    Flinchum, B. A.; Brudzinski, M. R.

    2011-12-01

    Non-volcanic tremor is a subtle ground vibration thought to be composed of a swarm of low-frequency earthquakes that represent fault slip on the interface between plates. By knowing when and where tremor is triggered, as well as when it is not triggered, we hope to grasp a better understanding of what conditions are necessary to induce fault slip. Based on recent reports of ambient tremor in South-Central Alaska during episodes of slow slip, we examined the time series during teleseismically recorded wave trains for eleven recent earthquakes with moment magnitude greater than 8.0. From these eleven events, we tested whether these events triggered NVT and where the tremor occurred. We initially performed a visual scan for tremor-like signals during incoming teleseismic phases using a 6-10 Hz bandpass filter on seismograms from stations over an area approximately 800 km by 600 km. We found five cases of triggered tremor that typically could be seen on stations such as PAX, HARP, MCK and KLU, although one additional event produced tremor that could only be seen on PAX. Next we designed an automated algorithm to both identify correlated NVT signals across several stations and locate the source of NVT. The automated system takes a few base stations where tremor signals have been seen during the visual search and then uses cross-correlation to progressively scan ten second portions of the entire teleseismic wave train at all other stations for similar bursts in NVT envelope functions. We find three events where the correlations exceed a correlation value greater than 65% at four or more stations at least 15 times during the duration of the event. The tremor locations during these three events falls into a separate cluster each time, but all occur near ambient tremor locations previously identified around the inferred eastern edge of subducting Yakutat terrane. Peak ground velocity (PGV) appears to be the primary factor for triggering tremor, with nearly all cases of

  5. LANDSAT demonstration/application and GIS integration in south central Alaska

    NASA Technical Reports Server (NTRS)

    Burns, A. W.; Derrenbacher, W.

    1981-01-01

    Automated geographic information systems were developed for two sites in Southcentral Alaska to serve as tests for both the process of integrating classified LANDSAT data into a comprehensive environmental data base and the process of using automated information in land capability/suitability analysis and environmental planning. The Big Lake test site, located approximately 20 miles north of the City of Anchorage, comprises an area of approximately 150 square miles. The Anchorage Hillside test site, lying approximately 5 miles southeast of the central part of the city, extends over an area of some 25 square miles. Map construction and content is described.

  6. Late Holocene glacial history of the Copper River Delta, coastal south-central Alaska, and controls on valley glacier fluctuations

    NASA Astrophysics Data System (ADS)

    Barclay, David J.; Yager, Elowyn M.; Graves, Jason; Kloczko, Michael; Calkin, Parker E.

    2013-12-01

    Fluctuations of four valley glaciers in coastal south-central Alaska are reconstructed for the past two millennia. Tree-ring crossdates on 216 glacially killed stumps and logs provide the primary age control, and are integrated with glacial stratigraphy, ages of living trees on extant landforms, and historic forefield photographs to constrain former ice margin positions. Sheridan Glacier shows four distinct phases of advance: in the 530s to c.640s in the First Millennium A.D., and the 1240s to 1280s, 1510s to 1700s, and c.1810s to 1860s during the Little Ice Age (LIA). The latter two LIA advances are also recorded on the forefields of nearby Scott, Sherman and Saddlebag glaciers. Comparison of the Sheridan record with other two-millennia long tree-ring constrained valley glacier histories from south-central Alaska and Switzerland shows the same four intervals of advance. These expansions were coeval with decreases in insolation, supporting solar irradiance as the primary pacemaker for centennial-scale fluctuations of mid-latitude valley glaciers prior to the 20th century. Volcanic aerosols, coupled atmospheric-oceanic systems, and local glacier-specific effects may be important to glacier fluctuations as supplemental forcing factors, for causing decadal-scale differences between regions, and as a climatic filter affecting the magnitude of advances.

  7. Limnology of Big Lake, south-central Alaska, 1983-84

    USGS Publications Warehouse

    Woods, Paul F.

    1992-01-01

    The limnological characteristics and trophic state of Big Lake in south-central Alaska were determined from the results of an intensive study during 1983-84. The study was begun in response to concern over the potential for eutrophication of Big Lake, which has experienced substantial residential development and recreational use because of its proximity to Anchorage. The east and west basins of the 1,213 square-hectometer lake were each visited 36 times during the 2-year study to obtain a wide variety of physical, chemical, and biological data. During 1984, an estimate was made of the lake's annual primary production. Big Lake was classified as oligotrophic on the basis of its annual mean values for total phosphorus (9.5 micrograms per liter), total nitrogen (209 micrograms per liter), chlorophyll-a (2.5 micrograms per liter), secchi-disc transparency (6.3 meters), and its mean daily integral primary production of 81.1 milligrams of carbon fixed per square meter. The lake was, however, uncharacteristic of oligotrophic lakes in that a severe dissolved-oxygen deficit developed within the hypolimnion during summer stratification and under winter ice cover. The summer dissolved-oxygen deficit resulted from the combination of strong and persistent thermal stratification, which developed within 1 week of the melting of the lake's ice cover in May, and the failure of the spring circulation to fully reaerate the hypolimnion. The autumn circulation did reaerate the entire water column, but the ensuing 6 months of ice and snow cover prevented atmospheric reaeration of the water column and led to development of the winter dissolved-oxygen deficit. The anoxic conditions that eventually developed near the lake bottom allowed the release of nutrients from the bottom sediments and facilitated ammonification reactions. These processes yielded hypolimnetic concentrations of nitrogen and phosphorus compounds, which were much larger than the oligotrophic concentrations measured

  8. A Detailed Geochemical Study of Island Arc Crust: The Talkeetna Arc Section, South-central Alaska

    NASA Astrophysics Data System (ADS)

    Greene, A. R.; Debari, S. M.; Kelemen, P. B.; Clift, P. D.; Blusztajn, J.

    2002-12-01

    The Talkeetna arc section in south-central Alaska is recognized as the exposed upper mantle and crust of an accreted, Late Triassic to Middle Jurassic island arc. Detailed geochemical studies of layered gabbronorite from the middle and lower crust of this arc and a diverse suite of volcanic and plutonic rocks from the middle and upper crust provide crucial data for understanding arc magma evolution. We also present new data on parental magma compositions for the arc. The deepest level of the arc section consists of residual mantle and ultramafic cumulates adjacent to garnet gabbro and basal gabbronorite interlayered with pyroxenite. The middle crust is primarily layered gabbronorite, ranging from anorthosite to pyroxenite in composition, and is the most widespread plutonic lithology. The upper mid crust is a heterogenous assemblage of dioritic to tonalitic rocks mixed with gabbro and intruded by abundant mafic dikes and chilled pillows. The upper crust of the arc is comprised of volcanic rocks of the Talkeetna Formation ranging from basalt to rhyolite. Most of these volcanic rocks have evolved compositions (<5% MgO, Mg# <60) and overlap the composition of intermediate to felsic plutonic rocks (<3.5% MgO, Mg# <45). However, several chilled mafic rocks and one basalt have primitive characteristics (>8% MgO, Mg# >60). Ion microprobe analyses of clinopyroxene in mid-crustal layered gabbronorites have parallel REE patterns with positive-sloping LREE segments (La/Sm(N)=0.05-0.17; mean 0.11) and flat HREE segments (5-25xchondrite; mean 10xchondrite). Liquids in REE equilibrium with the clinopyroxene in these gabbronorite cumulates were calculated in order to constrain parental magmas. These calculated liquids(La/Sm(N)=0.77-1.83; mean 1.26) all fall within the range of dike and volcanic rock(La/Sm(N)=0.78-2.12; mean 1.23) compositions. However, three lavas out of the 44 we have analyzed show strong HREE depletion, which is not observed in any of the liquid compositions

  9. Tectonic implications of paleomagnetic poles from Lower Tertiary Volcanic Rocks, south central Alaska

    NASA Astrophysics Data System (ADS)

    Hillhouse, John W.; Grommé, C. Sherman; Csejtey, Bela, Jr.

    1985-12-01

    We have determined the paleolatitude of lower Tertiary volcanic rocks in southern Alaska to measure possible poleward translation of the Wrangellia and the Peninsular terranes after 50 m.y. ago. Previous paleomagnetic studies have shown that in Triassic and Jurassic time these terranes were located near the equator and have moved at least 3000 km poleward relative to the North American craton. Our sample localities are in the northern Talkeetna Mountains in mildly deformed andesite and dacite flows (50.4, 51.3, 53.9, and 56.3 m.y. by K-Ar) that overlap Lower Cretaceous flysch, Lower Permian volcanic rocks of Wrangellia, and Upper Triassic pillow basalt of the Susitna terrane. Results from 26 cooling units (23 of reversed polarity and 3 of normal polarity) give a mean paleomagnetic pole at 69.5°N, 179.6°E, α95 = 12.2°. Stratigraphic sections from opposite limbs of a syncline yield directional paths that pass the fold test, satisfying a necessary condition for primary origin of the magnetization. The corresponding mean paleolatitude (76°N) of the northern Talkeetna Mountains is 8°±10° higher than the latitude predicted from the Eocene reference pole for North America. Therefore, northward drift of the Talkeetna superterrane, which is the amalgamation of the Wrangellia and Peninsular terranes during and after Middle Jurassic time, was probably complete by 50 m.y. ago. Our results are consistent with paleomagnetic poles from uppermost Cretaceous and Paleocene volcanic sequences in Denali National Park, the Lake Clark region, northern Bristol Bay region, and near McGrath. These poles generally lie south of the cratonic poles, suggesting that the region between the Kaltag, Bruin Bay, and Castle Mountain faults has rotated counterclockwise relative to North America since the early Eocene.

  10. Migration and wintering areas of glaucous-winged Gulls from south-central Alaska

    USGS Publications Warehouse

    Hatch, Shyla A.; Gill, V.A.; Mulcahy, D.M.

    2011-01-01

    We used satellite telemetry to investigate the migration patterns and wintering areas of Glaucouswinged Gulls (Larus glaucescens) from Middleton Island, Alaska, where this species' population increased tenfold from the 1970s to the 1990s. Fall migration spanned 11 weeks, including numerous stopovers en route, apparently for feeding. Spring migration from wintering sites to Middleton Island was shorter (4 weeks) and more direct. One juvenile spent several months in southern Prince William Sound. An adult spent several months near Craig, southeast Alaska, while three others overwintered in southern British Columbia. For all four wintering adults use of refuse-disposal sites was evident or strongly suggested. Commensalism with humans may have contributed to the increase on Middleton, but a strong case can also be made for a competing explanation-regional recruitment of gulls to high-quality nesting habitat in Alaska created after the earthquake of 1964. An analysis of band returns reveals broad overlap in the wintering grounds of gulls from different Alaska colonies and of gulls banded on the west coast from British Columbia to California. The seasonal movement of many gulls from Alaska is decidedly migratory, whereas gulls from British Columbia, Washington, and Oregon disperse locally in winter. ?? The Cooper Ornithological Society 2011.

  11. Migration And wintering areas Of Glaucous-winged Gulls From south-central Alaska

    USGS Publications Warehouse

    Hatch, Scott A.; Gill, V.A.; Mulcahy, Daniel M.

    2011-01-01

    We used satellite telemetry to investigate the migration patterns and wintering areas of Glaucous-winged Gulls (Larus glaucescens) from Middleton Island, Alaska, where this species' population increased tenfold from the 1970s to the 1990s. Fall migration spanned 11 weeks, including numerous stopovers en route, apparently for feeding. Spring migration from wintering sites to Middleton Island was shorter (4 weeks) and more direct. One juvenile spent several months in southern Prince William Sound. An adult spent several months near Craig, southeast Alaska, while three others overwintered in southern British Columbia. For all four wintering adults use of refuse-disposal sites was evident or strongly suggested. Commensalism with humans may have contributed to the increase on Middleton, but a strong case can also be made for a competing explanation-regional recruitment of gulls to high-quality nesting habitat in Alaska created after the earthquake of 1964. An analysis of band returns reveals broad overlap in the wintering grounds of gulls from different Alaska colonies and of gulls banded on the west coast from British Columbia to California. The seasonal movement of many gulls from Alaska is decidedly migratory, whereas gulls from British Columbia, Washington, and Oregon disperse locally in winter.

  12. Role of lake regulation on glacier fed rivers in enhancing salmon productivity: The Cook Inlet watershed south central Alaska, USA

    USGS Publications Warehouse

    Hupp, C.R.

    2000-01-01

    Rivers fed by glaciers constitute a major part of the freshwater runoff into the Cook Inlet basin of south-central Alaska. This basin is very important to the economy of the State of Alaska because it is home to more than half of the population and it supports multi-million dollar commercial, subsistence and sport fisheries. Hence an understanding of how glacial runoff influences biological productivity is important for managing rivers that drain into Cook Inlet. This paper examines the ways in which the regulation of glacier-fed rivers by proglacial lakes affects salmon productivity, with particular reference to the Kenai River. Salmon escapement per unit channel length on the Kenai River is between two and ten times that found for rain-and-snowmelt dominated rivers and glacier-fed rivers lacking lake regulation. Lakes are shown to influence biological processes in glacier-fed rivers by attenuating peak flows, sustaining high flows throughout the summer, supplementing winter low flows, settling suspended sediment, and increasing river temperatures. Downstream from large lakes, glacier-fed rivers are less disturbed, channels are relatively stable and have well-developed salmonid habitats. The positive influences are indicated by the high diversity and abundances of benthic macroinvertebrates, which are important food resources for juvenile salmonids. High summer flows allow access for up-river salmon runs and lakes also provide both overwintering and rearing habitat. Copyright ?? 2000 John Wiley & Sons, Ltd.Rivers fed by glaciers constitute a major part of the freshwater runoff into the Cook Inlet basin of south-central Alaska. This basin is very important to the economy of the State of Alaska because it is home to more than half of the population and it supports multi-million dollar commercial, subsistence and sport fisheries. Hence an understanding of how glacial runoff influences biological productivity is important for managing rivers that drain into Cook Inlet

  13. Density and magnetic suseptibility values for rocks in the Talkeetna Mountains and adjacent region, south-central Alaska

    USGS Publications Warehouse

    Sanger, Elizabeth A.; Glen, Jonathan M.G.

    2003-01-01

    This report presents a compilation and statistical analysis of 306 density and 706 magnetic susceptibility measurements of rocks from south-central Alaska that were collected by U.S. Geological Survey (USGS) and Alaska Division of Geological and Geophysical Surveys (ADGGS) scientists between the summers of 1999 and 2002. This work is a product of the USGS Talkeetna Mountains Transect Project and was supported by USGS projects in the Talkeetna Mountains and Iron Creek region, and by Bureau of Land Management (BLM) projects in the Delta River Mining District that aim to characterize the subsurface structures of the region. These data were collected to constrain potential field models (i.e., gravity and magnetic) that are combined with other geophysical methods to identify and model major faults, terrane boundaries, and potential mineral resources of the study area. Because gravity and magnetic field anomalies reflect variations in the density and magnetic susceptibility of the underlying lithology, these rock properties are essential components of potential field modeling. In general, the average grain density of rocks in the study region increases from sedimentary, felsic, and intermediate igneous rocks, to mafic igneous and metamorphic rocks. Magnetic susceptibility measurements performed on rock outcrops and hand samples from the study area also reveal lower magnetic susceptibilities for sedimentary and felsic intrusive rocks, moderate susceptibility values for metamorphic, felsic extrusive, and intermediate igneous rocks, and higher susceptibility values for mafic igneous rocks. The density and magnetic properties of rocks in the study area are generally consistent with general trends expected for certain rock types.

  14. Age-specific reproduction in female sea otters (Enhydra lutris) from south-central Alaska: analysis of reproductive tracts

    USGS Publications Warehouse

    Bodkin, J.; Mulcahy, D.; Lensink, C.

    1993-01-01

    We estimated age at sexual maturity and age-specific reproductive rates by examining carcasses and reproductive tracts from 177 female sea otters (Enhydra lutris). Carcasses were recovered from south-central Alaska, Primarily from western Prince William Sound, as a result of the T/V Exxon Valdez oit spill in 1989. We found 65% of our sample to be sexually mature. Sexual maturity was first attained at age 2. The proportion of sexually mature animals increased from 30% at age 2 to 100% at age 5. Annual reproductive rates increased from 22% at age 2 to 78% at age 5 and remained relatively stable (75-88%) through to age 15. the sex ratio (female:male) of 49 fetal sea otters was 18:37 and differed significantly from parity. Females younger than 8 tended to produce more female fetuses, while older mothers did not. Our estimates of the reproductive characteristics of female sea otters obtained by examination of reproductive tracts wre similiar to those reported in the literature based on in situ observations of marked individuals.

  15. Rock-Eval pyrolysis and vitrinite reflectance results from the Sheep Creek 1 well, Susitna basin, south-central Alaska

    USGS Publications Warehouse

    Stanley, Richard G.; Lillis, Paul G.; Pawlewicz, Mark J.; Haeussler, Peter J.

    2014-01-01

    We used Rock-Eval pyrolysis and vitrinite reflectance to examine the petroleum source potential of rock samples from the Sheep Creek 1 well in the Susitna basin of south-central Alaska. The results show that Miocene nonmarine coal, carbonaceous shale, and mudstone are potential sources of hydrocarbons and are thermally immature with respect to the oil window. In the samples that we studied, coals are more organic-rich and more oil-prone than carbonaceous shales and silty mudstones, which appear to be potential sources of natural gas. Lithologically similar rocks may be present in the deeper parts of the subsurface Susitna basin located west of the Sheep Creek 1 well, where they may have been buried deeply enough to generate oil and (or) gas. The Susitna basin is sparsely drilled and mostly unexplored, and no commercial production of hydrocarbons has been obtained. However, the existence of potential source rocks of oil and gas, as shown by our Rock-Eval results, suggests that undiscovered petroleum accumulations may be present in the Susitna basin.

  16. Range overlap and individual movements during breeding season influence genetic relationships of caribou herds in south-central Alaska

    USGS Publications Warehouse

    Roffler, Gretchen H.; Adams, Layne G.; Talbot, Sandra L.; Sage, George K.; Dale, Bruce W.

    2012-01-01

    North American caribou (Rangifer tarandus) herds commonly exhibit little nuclear genetic differentiation among adjacent herds, although available evidence supports strong demographic separation, even for herds with seasonal range overlap. During 1997–2003, we studied the Mentasta and Nelchina caribou herds in south-central Alaska using radiotelemetry to determine individual movements and range overlap during the breeding season, and nuclear and mitochondrial DNA (mtDNA) markers to assess levels of genetic differentiation. Although the herds were considered discrete because females calved in separate regions, individual movements and breeding-range overlap in some years provided opportunity for male-mediated gene flow, even without demographic interchange. Telemetry results revealed strong female philopatry, and little evidence of female emigration despite overlapping seasonal distributions. Analyses of 13 microsatellites indicated the Mentasta and Nelchina herds were not significantly differentiated using both traditional population-based analyses and individual-based Bayesian clustering analyses. However, we observed mtDNA differentiation between the 2 herds (FSTM = 0.041, P

  17. Population genetic structure of moose (Alces Alces) of South-central Alaska.

    USGS Publications Warehouse

    Wilson, Robert E.; McDonough, John T.; Barboza, Perry S.; Talbot, Sandra L.; Farley, Sean D.

    2015-01-01

    The location of a population can influence its genetic structure and diversity by impacting the degree of isolation and connectivity to other populations. Populations at range margins areoften thought to have less genetic variation and increased genetic structure, and a reduction in genetic diversity can have negative impacts on the health of a population. We explored the genetic diversity and connectivity between 3 peripheral populations of moose (Alces alces) with differing potential for connectivity to other areas within interior Alaska. Populations on the Kenai Peninsula and from the Anchorage region were found to be significantly differentiated (FST= 0.071, P < 0.0001) with lower levels of genetic diversity observed within the Kenai population. Bayesian analyses employing assignment methodologies uncovered little evidence of contemporary gene flow between Anchorage and Kenai, suggesting regional isolation. Although gene flow outside the peninsula is restricted, high levels of gene flow were detected within the Kenai that is explained by male-biased dispersal. Furthermore, gene flow estimates differed across time scales on the Kenai Peninsula which may have been influenced by demographic fluctuations correlated, at least in part, with habitat change.

  18. Preliminary interpretation of industry two-dimensional seismic data from Susitna Basin, south-central Alaska

    USGS Publications Warehouse

    Lewis, Kristen A.; Potter, Christopher J.; Shah, Anjana K.; Stanley, Richard G.; Haeussler, Peter J.; Saltus, Richard W.

    2015-01-01

    The eastern seismic lines show evidence of numerous short-wavelength antiforms that appear to correspond to a series of northeast-trending lineations observed in aeromagnetic data, which have been interpreted as being due to folding of Paleogene volcanic strata. The eastern side of the basin is also cut by a number of reverse faults and thrust faults, the majority of which strike north-south. The western side of the Susitna Basin is cut by a series of regional reverse faults and is characterized by synformal structures in two fault blocks between the Kahiltna River and Skwentna faults. These synforms are progressively deeper to the west in the footwalls of the east-vergent Skwentna and northeast-vergent Beluga Mountain reverse faults. Although the seismic data are limited to the south, we interpret a potential regional south-southeast-directed reverse fault striking east-northeast on the east side of the basin that may cross the entire southern portion of the basin.

  19. Paleomagnetism of Cretaceous and Paleocene sedimentary rocks across the Castle Mountain Fault, south central Alaska

    NASA Astrophysics Data System (ADS)

    Stamatakos, John A.; Kodama, K. P.; Vittorio, L. F.; Pavlis, T. L.

    Paleomagnetic and rock magnetic analyses on 217 samples from 13 sites in the Paleocene Chickaloon Formation south of the Castle Mountain Fault and 111 samples from 9 sites in the coeval, but lithologically distinct, Arkose Ridge Formation north of this fault indicate that these rocks contain a pre-folding magnetization carried by fine grained (<1.0μm) single domain magnetite. Secondary magnetizations are common, possibly as the result of the presence of authigenic or hydrothermal pyrrhotite. Although characteristic magnetizations were isolated for the Chickaloon and Arkose Ridge rocks, the best results were obtained from demagnetization plane analysis which estimates the location of the paleomagnetic pole for the Chickaloon Formation at 50.5°N, 277.2°E, δm = 12.2°, δP = 7.77deg;, and a paleomagnetic pole for the Arkose Ridge Formation at 60.4°N, 138.6°E, δm = 11.6°, δp = 6.4°. These results suggest that there is no paleomagnetically discernible latitudinal offset across the Castle Mountain Fault since Paleocene time, but that both the Chickaloon and Arkose Ridge rocks, as part of the Peninsular terrane, originated approximately 1600±1200 km south of their present position with respect to North America. One possible explanation of these data is that the Peninsular terrane was accreted to North America at mid-latitudes in the Cretaceous and was subsequently translated northward by right-lateral strike-slip faulting parallel to the North American margin. Hence, the Arkose Ridge and Chickaloon results may be indicative of the cumulative right-hand displacement occurring on these faults since Paleocene time. However, a calculation using the pole to the small circle fit of the present-day curvature of the Tintina-Northern Rocky Mountain Trench and Denali fault systems, and the maximum amount of structurally estimated offset across these fault systems, indicates that motion on these faults can account for no more than half of the paleomagnetically observed

  20. Field-trip guide to volcanic and volcaniclastic deposits of the lower Jurassic Talkeetna formation, Sheep Mountain, south-central Alaska

    USGS Publications Warehouse

    Draut, Amy E.; Clift, Peter D.; Blodgett, Robert B.

    2006-01-01

    This guide provides information for a one-day field trip in the vicinity of Sheep Mountain, just north of the Glenn Highway in south-central Alaska. The Lower Jurassic Talkeetna Formation, consisting of extrusive volcanic and volcaniclastic sedimentary rocks of the Talkeetna arc complex, is exposed on and near Sheep Mountain. Field-trip stops within short walking distance of the Glenn Highway (approximately two hours’ drive from Anchorage) are described, which will be visited during the Geological Society of America Penrose meeting entitled Crustal Genesis and Evolution: Focus on Arc Lower Crust and Shallow Mantle, held in Valdez, Alaska, in July 2006. Several additional exposures of the Talkeetna Formation on other parts of Sheep Mountain that would need to be accessed with longer and more strenuous walking or by helicopter are also mentioned.

  1. Genetic characterization of Kenai brown bears (Ursus arctos): Microsatellite and mitochondrial DNA control region variation in brown bears of the Kenai Peninsula, south central Alaska

    USGS Publications Warehouse

    Jackson, J.V.; Talbot, S.L.; Farley, S.

    2008-01-01

    We collected data from 20 biparentally inherited microsatellite loci, and nucleotide sequence from the maternally inherited mitochondrial DNA (mtDNA) control region, to determine levels of genetic variation of the brown bears (Ursus arctos L., 1758) of the Kenai Peninsula, south central Alaska. Nuclear genetic variation was similar to that observed in other Alaskan peninsular populations. We detected no significant inbreeding and found no evidence of population substructuring on the Kenai Peninsula. We observed a genetic signature of a bottleneck under the infinite alleles model (IAM), but not under the stepwise mutation model (SMM) or the two-phase model (TPM) of microsatellite mutation. Kenai brown bears have lower levels of mtDNA haplotypic diversity relative to most other brown bear populations in Alaska. ?? 2008 NRC.

  2. Frozen debris lobes, permafrost slope instability, and a potential infrastructure hazard in the south-central Brooks Range of Alaska

    NASA Astrophysics Data System (ADS)

    Daanen, R. P.; Darrow, M.; Grosse, G.; Jones, B. M.

    2012-12-01

    Here we report on investigations carried out at unusual debris mass-movement features (frozen debris lobes) on permafrost slopes in the south central portion of the Brooks Range of northern Alaska. The features under investigation are located in mountainous terrain near the southern border of continuous permafrost. The frozen debris lobes consist mainly of boulders, cobles, platy gravel sand and silt frozen debris derived from weathering mountain tops. The general dimensions of these lobes are either lobate or tongue shaped with widths up to 500 m and lengths up to 1200 m. In accumulation zones where slopes converge, the debris slowly moves as solifluction lobes, mud flows and potentially sliding toward the valley. These features were previously referred to as stable rock glaciers in the past, as evidenced by a dense cover of vegetation, and exhibiting no known downslope movement. Our investigations however, have shown that these features are indeed moving downslope as a result of creep, slumping, viscous flow, blockfall and leaching of fines in the summer; and in cold seasons by creep and sliding of frozen sediment slabs. Movement indicators observed in the field include toppling trees, slumps and scarps, detachment slides, striation marks on frozen sediment slabs, recently buried trees and other vegetation, mudflows, and large cracks in the lobe surface. Ground-based measurements on one frozen debris-lobe over three years (2008-2010) revealed average movement rates of approximately 1 cm day-1, which is substantially larger than rates measured in historic aerial photography from the 1950s to 1980s. Current observations , through lidar, ifsar, insar and ground based measurements using boreholes, geophysics and repeat photography of these features show an increase in movement activity that could be the result of rising summer temperatures in the region. Warming of ice rich permafrost slopes and frozen debris lobes in the Brooks Range pose a direct threat to the

  3. Role of lake regulation on glacier-fed rivers in enhancing salmon productivity: the Cook Inlet watershed, south-central Alaska, USA

    NASA Astrophysics Data System (ADS)

    Dorava, Joseph M.; Milner, Alexander M.

    2000-10-01

    Rivers fed by glaciers constitute a major part of the freshwater runoff into the Cook Inlet basin of south-central Alaska. This basin is very important to the economy of the State of Alaska because it is home to more than half of the population and it supports multi-million dollar commercial, subsistence and sport fisheries. Hence an understanding of how glacial runoff influences biological productivity is important for managing rivers that drain into Cook Inlet. This paper examines the ways in which the regulation of glacier-fed rivers by proglacial lakes affects salmon productivity, with particular reference to the Kenai River. Salmon escapement per unit channel length on the Kenai River is between two and ten times that found for rain-and-snowmelt dominated rivers and glacier-fed rivers lacking lake regulation.Lakes are shown to influence biological processes in glacier-fed rivers by attenuating peak flows, sustaining high flows throughout the summer, supplementing winter low flows, settling suspended sediment, and increasing river temperatures. Downstream from large lakes, glacier-fed rivers are less disturbed, channels are relatively stable and have well-developed salmonid habitats. The positive influences are indicated by the high diversity and abundances of benthic macroinvertebrates, which are important food resources for juvenile salmonids. High summer flows allow access for up-river salmon runs and lakes also provide both overwintering and rearing habitat.

  4. Rapid movement of frozen debris-lobes: implications for permafrost degradation and slope instability in the south-central Brooks Range, Alaska

    NASA Astrophysics Data System (ADS)

    Daanen, R. P.; Grosse, G.; Darrow, M. M.; Hamilton, T. D.; Jones, B. M.

    2012-05-01

    We present the results of a reconnaissance investigation of unusual debris mass-movement features on permafrost slopes that pose a potential infrastructure hazard in the south-central Brooks Range, Alaska. For the purpose of this paper, we describe these features as frozen debris-lobes. We focus on the characterisation of frozen debris-lobes as indicators of various movement processes using ground-based surveys, remote sensing, field and laboratory measurements, and time-lapse observations of frozen debris-lobe systems along the Dalton Highway. Currently, some frozen debris-lobes exceed 100 m in width, 20 m in height and 1000 m in length. Our results indicate that frozen debris-lobes have responded to climate change by becoming increasingly active during the last decades, resulting in rapid downslope movement. Movement indicators observed in the field include toppling trees, slumps and scarps, detachment slides, striation marks on frozen sediment slabs, recently buried trees and other vegetation, mudflows, and large cracks in the lobe surface. The type and diversity of observed indicators suggest that the lobes likely consist of a frozen debris core, are subject to creep, and seasonally unfrozen surface sediment is transported in warm seasons by creep, slumping, viscous flow, blockfall and leaching of fines, and in cold seasons by creep and sliding of frozen sediment slabs. Ground-based measurements on one frozen debris-lobe over three years (2008-2010) revealed average movement rates of approximately 1 cm day-1, which is substantially larger than rates measured in historic aerial photography from the 1950s to 1980s. We discuss how climate change may further influence frozen debris-lobe dynamics, potentially accelerating their movement. We highlight the potential direct hazard that one of the studied frozen debris-lobes may pose in the coming years and decades to the nearby Trans Alaska Pipeline System and the Dalton Highway, the main artery for transportation

  5. Rapid movement of frozen debris-lobes: implications for permafrost degradation and slope instability in the south-central Brooks Range, Alaska

    USGS Publications Warehouse

    Daanen, R.P.; Grosse, G.; Darrow, M.M.; Hamilton, T.D.; Jones, Benjamin M.

    2012-01-01

    We present the results of a reconnaissance investigation of unusual debris mass-movement features on permafrost slopes that pose a potential infrastructure hazard in the south-central Brooks Range, Alaska. For the purpose of this paper, we describe these features as frozen debris-lobes. We focus on the characterisation of frozen debris-lobes as indicators of various movement processes using ground-based surveys, remote sensing, field and laboratory measurements, and time-lapse observations of frozen debris-lobe systems along the Dalton Highway. Currently, some frozen debris-lobes exceed 100 m in width, 20 m in height and 1000 m in length. Our results indicate that frozen debris-lobes have responded to climate change by becoming increasingly active during the last decades, resulting in rapid downslope movement. Movement indicators observed in the field include toppling trees, slumps and scarps, detachment slides, striation marks on frozen sediment slabs, recently buried trees and other vegetation, mudflows, and large cracks in the lobe surface. The type and diversity of observed indicators suggest that the lobes likely consist of a frozen debris core, are subject to creep, and seasonally unfrozen surface sediment is transported in warm seasons by creep, slumping, viscous flow, blockfall and leaching of fines, and in cold seasons by creep and sliding of frozen sediment slabs. Ground-based measurements on one frozen debris-lobe over three years (2008–2010) revealed average movement rates of approximately 1 cm day−1, which is substantially larger than rates measured in historic aerial photography from the 1950s to 1980s. We discuss how climate change may further influence frozen debris-lobe dynamics, potentially accelerating their movement. We highlight the potential direct hazard that one of the studied frozen debris-lobes may pose in the coming years and decades to the nearby Trans Alaska Pipeline System and the Dalton Highway, the main artery for transportation

  6. Effects of the earthquake of March 27, 1964, on air and water transport, communications, and utilities systems in south-central Alaska: Chapter B in The Alaska earthquake, March 27, 1964: effects on transportation, communications, and utilities

    USGS Publications Warehouse

    Eckel, Edwin B.

    1967-01-01

    The earthquake of March 27, 1964, wrecked or severely hampered all forms of transportation, all utilities, and all communications systems over a very large part of south-central Alaska. Effects on air transportation were minor as compared to those on the water, highway, and railroad transport systems. A few planes were damaged or wrecked by seismic vibration or by flooding. Numerous airport facilities were damaged by vibration or by secondary effects of the earthquake, notably seismic sea and landslide-generated waves, tectonic subsidence, and compaction. Nearly all air facilities were partly or wholly operational within a few hours after the earthquake. The earthquake inflicted enormous damage on the shipping industry, which is indispensable to a State that imports fully 90 percent of its requirements—mostly by water—and whose largest single industry is fishing. Except for those of Anchorage, all port facilities in the earthquake-affected area were destroyed or made inoperable by submarine slides, waves, tectonic uplift, and fire. No large vessels were lost, but more than 200 smaller ones (mostly crab or salmon boats) were lost or severely damaged. Navigation aids were destroyed, and hitherto well-known waterways were greatly altered by uplift or subsidence. All these effects wrought far-reaching changes in the shipping economy of Alaska, many of them to its betterment. Virtually all utilities and communications in south-central Alaska were damaged or wrecked by the earthquake, but temporary repairs were effected in remarkably short times. Communications systems were silenced almost everywhere by loss of power or by downed lines; their place was quickly taken by a patchwork of self-powered radio transmitters. A complex power-generating system that served much of the stricken area from steam, diesel, and hydrogenerating plants was disrupted in many places by vibration damage to equipment and by broken transmission lines. Landslides in Anchorage broke gas

  7. A deglacial and Holocene record of climate variability in south-central Alaska from stable oxygen isotopes and plant macrofossils in peat

    USGS Publications Warehouse

    Jones, Miriam C.; Wooller, Matthew J.; Peteet, Dorothy M.

    2014-01-01

    We used stable oxygen isotopes derived from bulk peat (δ18OTOM), in conjunction with plant macrofossils and previously published carbon accumulation records, in a ∼14,500 cal yr BP peat core (HT Fen) from the Kenai lowlands in south-central Alaska to reconstruct the climate history of the area. We find that patterns are broadly consistent with those from lacustrine records across the region, and agree with the interpretation that major shifts in δ18OTOM values indicate changes in strength and position of the Aleutian Low (AL), a semi-permanent low-pressure cell that delivers winter moisture to the region. We find decreased strength or a more westerly position of the AL (relatively higher δ18OTOM values) during the Bølling-Allerød, Holocene Thermal Maximum (HTM), and late Holocene, which also correspond to warmer climate regimes. These intervals coincide with greater peat preservation and enhanced carbon (C) accumulation rates at the HT Fen and with peatland expansion across Alaska. The HTM in particular may have experienced greater summer precipitation as a result of an enhanced Pacific subtropical high, a pattern consistent with modern δ18O values for summer precipitation. The combined warm summer temperatures and greater summer precipitation helped promote the observed rapid peat accumulation. A strengthened AL (relatively lower δ18OTOM values) is most evident during the Younger Dryas, Neoglaciation, and the Little Ice Age, consistent with lower peat preservation and C accumulation at the HT Fen, suggesting less precipitation reaches the leeward side of the Kenai Mountains during periods of enhanced AL strength. The peatlands on the Kenai Peninsula thrive when the AL is weak and the contribution of summer precipitation is higher, highlighting the importance of precipitation seasonality in promoting peat accumulation. This study demonstrates that δ18OTOM values in peat can be applied toward understand large-scale shifts in atmospheric circulation

  8. Structural geology and kinematics associated with the collision of the Wrangellia composite terrane and North America, south-central Alaska

    NASA Astrophysics Data System (ADS)

    Bier, Sara Elizabeth

    The collision of the Insular superterrane, and thus, the Wrangellia composite terrane (WCT), with the Mesozoic margin of North America is one of the most important, yet enigmatic events in the tectonic history of North American cordillera. The location and therefore the nature of the collision of the Insular superterrane with North America remains controversial. In southern Alaska, the suture zone between the WCT and North America consists of the Kahiltna assemblage, Jurassic-Cretaceous submarine fan deposits. Structural investigation of the Kahiltna assemblage provides additional data on the kinematics of the collision and suggests an oblique collision with a significant component of right-lateral shearing. The first study of the dissertation presents the results across a transect at the northern end of Broad Pass where the depositional and deformational history of three tectonostratigraphic units enables determination of the tectonic evolution of the suture zone. The Reindeer Hills exposes melange units that include oceanic lithologies and represent a remnant of an accretionary complex that formed during subduction prior to the collision of the WCT. Structures within the Kahiltna assemblage in the Talkeetna Mountains indicate oblique northwest-directed thrusting and right-lateral shear during the collision of the WCT. The Jack River conglomerate, a fluvial clast-supported conglomerate unconformably overlies the Reindeers Hills melange and represents uplift, erosion, and deposition late in the collision. The second study is on the other side of Broad Pass, in the southern Alaska Range, and consists of a composite transect across the Peters and Dutch Hills and Chelatna Lake. Horizontal stretching lineations and steeply-dipping foliation indicate that deformation occurred during transpression as a result of an oblique collision. Strain analysis of pressure shadows indicate a counterclockwise rotation of the extension direction and thus, right-lateral shearing during

  9. Kittlitz's and Marbled Murrelets in Kenai Fjords National Park, South-Central Alaska: At-Sea Distribution, Abundance, and Foraging Habitat, 2006-08

    USGS Publications Warehouse

    Arimitsu, M.L.; Piatt, J.F.; Romano, Marc D.; Madison, E.N.; Conaway, J.S.

    2010-01-01

    Kittlitz's murrelets (Brachyramphus brevirostris) and marbled murrelets (B. marmoratus) are small diving seabirds and are of management concern because of population declines in coastal Alaska. In 2006-08, we conducted a study in Kenai Fjords National Park, south-central Alaska, to estimate the recent population size of Brachyramphus murrelets, to evaluate productivity based on juvenile to adult ratios during the fledgling season, and to describe and compare their use of marine habitat. We also attempted a telemetry study to examine Kittlitz's murrelet nesting habitat requirements and at-sea movements. We estimated that the Kittlitz's murrelet population was 671 ? 144 birds, and the marbled murrelet population was 5,855 ? 1,163 birds. Kittlitz's murrelets were limited to the heads of three fjords with tidewater glaciers, whereas marbled murrelets were more widely distributed. Population estimates for both species were lower in 2007 than in 2006 and 2008, possibly because of anomalous oceanographic conditions that may have delayed breeding phenology. During late season surveys, we observed few hatch-year marbled murrelets and only a single hatch-year Kittlitz's murrelet over the course of the study. Using radio telemetry, we found a likely Kittlitz's murrelet breeding site on a mountainside bordering one of the fjords. We never observed radio-tagged Kittlitz's murrelets greater than 10 kilometer from their capture sites, suggesting that their foraging range during breeding is narrow. We observed differences in oceanography between fjords, reflecting differences in sill characteristics and orientation relative to oceanic influence. Acoustic biomass, a proxy for zooplankton and small schooling fish, generally decreased with distance from glaciers in Northwestern Lagoon, but was more variable in Aialik Bay where dense forage fish schools moved into glacial areas late in the summer. Pacific herring (Clupea pallasii), capelin (Mallotus villosus) and Pacific sand lance

  10. A Deglacial and Holocene Record of Climate Variability in South-Central Alaska from Stable Oxygen Isotopes and Plant Macrofossils in Peat

    NASA Technical Reports Server (NTRS)

    Jones, Miriam C.; Wooller, Matthew; Peteet, Dorothy M.

    2014-01-01

    We used stable oxygen isotopes derived from bulk peat (delta-O-18(sub TOM) in conjunction with plant macrofossils and previously published carbon accumulation records, in a approximately14,500 cal yr BP peat core (HT Fen) from the Kenai lowlands in south-central Alaska to reconstruct the climate history of the area. We find that patterns are broadly consistent with those from lacustrine records across the region, and agree with the interpretation that major shifts in delta-O-18(sub TOM) values indicate changes in strength and position of the Aleutian Low (AL), a semi-permanent low-pressure cell that delivers winter moisture to the region. We find decreased strength or a more westerly position of the AL (relatively higher delta-O-18(sub TOM) values) during the Bolling-Allerod, Holocene Thermal Maximum (HTM), and late Holocene, which also correspond to warmer climate regimes. These intervals coincide with greater peat preservation and enhanced carbon (C) accumulation rates at the HT Fen and with peatland expansion across Alaska. The HTM in particular may have experienced greater summer precipitation as a result of an enhanced Pacific subtropical high, a pattern consistent with modern delta-O-18 values for summer precipitation. The combined warm summer temperatures and greater summer precipitation helped promote the observed rapid peat accumulation. A strengthened AL (relatively lower delta-O-18(sub TOM) values) is most evident during the Younger Dryas, Neoglaciation, and the Little Ice Age, consistent with lower peat preservation and C accumulation at the HT Fen, suggesting less precipitation reaches the leeward side of the Kenai Mountains during periods of enhanced AL strength. The peatlands on the Kenai Peninsula thrive when the AL is weak and the contribution of summer precipitation is higher, highlighting the importance of precipitation seasonality in promoting peat accumulation. This study demonstrates that delta-O-18(sub TOM) values in peat can be applied

  11. Landslide Hazard Mapping Using Ground-based Interferometric Radar in the Fjords of South-Central Alaska

    NASA Astrophysics Data System (ADS)

    Balazs, M. S.; Meyer, F. J.; Bollian, T.; Wolken, G. J.; Prakash, A.

    2013-12-01

    The cities of Seward and Whittier, Alaska are situated at the base of steep walls within two fjords located on the Kenai Peninsula. Historic events have shown that the combination of terrain, geology, and vegetation are factors which can lead to significant events of erosion in the surrounding slopes during periods of heavy rainfall. While other remote sensing techniques have been shown to be useful for accessing landslide hazards, local surface processes may be better understood to create more accurate hazard maps and predictive models by using data gained from interferometric radar. To gain perspective into where, and at which speed, slopes are deforming, we utilize the GPRI-2 terrestrial interferometric radar system which transmits signals in the Ku band. The GPRI-2 portable radar unit has several advantages to space-borne radar, including relative freedom of site selection and regions to target, ability to determine temporal baselines, and repeat acquisitions which can be collected with a zero spatial-baseline. There are however, problems which need to be addressed when using such a system in the fjord environments, and in particular for monitoring slope deformation in these areas. Foremost, the noise that is attributed to the atmosphere is of great concern as it is sometimes required to position the radar several kilometers away from the target, across open water. We offer our results of correcting for this interference and report the results. Secondly, we address the issue of repeat acquisitions over long periods of time, which is needed to detect movements in the slope, and report on the decorrelation of the signal in the various land cover types in the study areas. Finally, we offer suggestions of the usefulness of such a system to detect slope deformation in similar environments.

  12. Geochemistry of siliciclastic rocks in the Peninsular, Chugach, and Prince William terranes: Implications for the tectonic evolution of south central Alaska

    SciTech Connect

    Gilbert, S.A.; Casey, J.F. . Dept. of Geosciences); Bradley, D. . Branch of Alaskan Geology); Kusky, T. . Dept. of Geology)

    1992-01-01

    According to some interpretations, south-central Alaska consists of a series of unrelated terranes juxtaposed by dominantly strike-slip motions some time after formation. Alternatively, these so-called terranes may be related components of a seaward-facing arc, forearc, and accretionary prism. To shed new light on the tectonic history of this area, 150 samples of siliciclastic rocks were analyzed for major, trace, and rare earth elements (REE). Shales were sampled from the Upper Cretaceous Matanuska and Paleogene Chickaloon Fms. of the Peninsular Terrane (forearc basin); argillaceous melange matrix from the Mesozoic McHugh Complex and slate from turbidites of the Upper Cretaceous Valdez Group of the Chugach Terrane (landward part of accretionary prism); and slate from turbidites of the Paleogene Orea Group of the Prince William Terrane (seaward part of accretionary prism). One tectonic model that may fit these geochemical data requires an early linkage between the Peninsular and Chugach-Prince William composite terranes. The geochemical signatures suggest that the McHugh Complex was derived from a mafic volcanic source and may represent an early accretionary stage of sediments derived from an oceanic arc. The progressive continental enrichment of the Valdez and Orca Groups may reflect later accretionary processes during and/or after the collision of the Talkectna arc with the North American continent. The similar increasingly continental source documented in the geochemistry of the forearc basin shales of the Matanuska and Chickaloon Fms. may suggest: that the presently defined Peninsular, Chugach, and Prince William terranes collectively represent one continuously evolving, seaward facing arc, forearc, and accretionary prism complex.

  13. Assessment of the Coal-Bed Gas Total Petroleum System in the Cook Inlet-Susitna region, south-central Alaska

    USGS Publications Warehouse

    Rouse, William A.; Houseknecht, David W.

    2012-01-01

    The Cook Inlet-Susitna region of south-central Alaska contains large quantities of gas-bearing coal of Tertiary age. The U.S. Geological Survey in 2011 completed an assessment of undiscovered, technically recoverable coal-bed gas resources underlying the Cook Inlet-Susitna region based on the total petroleum system (TPS) concept. The Cook Inlet Coal-Bed Gas TPS covers about 9,600,000 acres and comprises the Cook Inlet basin, Matanuska Valley, and Susitna lowland. The TPS contains one assessment unit (AU) that was evaluated for coal-bed gas resources between 1,000 and 6,000 feet in depth over an area of about 8,500,000 acres. Coal beds, which serve as both the source and reservoir for natural gas in the AU, were deposited during Paleocene-Pliocene time in mires associated with a large trunk-tributary fluvial system. Thickness of individual coal beds ranges from a few inches to more than 50 feet, with cumulative coal thickness of more than 800 feet in the western part of the basin. Coal rank ranges from lignite to subbituminous, with vitrinite reflectance values less than 0.6 percent throughout much of the AU. The AU is considered hypothetical because only a few wells in the Matanuska Valley have tested the coal-bed reservoirs, so the use of analog coal-bed gas production data was necessary for this assessment. In order to estimate reserves that might be added in the next 30 years, coal beds of the Upper Fort Union Formation in the Powder River Basin of Wyoming and Montana were selected as the production analog for Tertiary coal beds in the Cook Inlet-Susitna region. Upper Fort Union coal beds have similar rank (lignite to subbituminous), range of thickness, and coal-quality characteristics as coal beds of the Tertiary Kenai Group. By use of this analog, the mean total estimate of undiscovered coal-bed gas in the Tertiary Coal-Bed Gas AU is 4.674 trillion cubic feet (TCF) of gas.

  14. Significance of a near-source tephra-stratigraphic sequence to the eruptive history of Hayes Volcano, south-central Alaska

    USGS Publications Warehouse

    Wallace, Kristi; Coombs, Michelle L.; Hayden, Leslie A.; Waythomas, Christopher F.

    2014-01-01

    Bluffs along the Hayes River valley, 31 km northeast and 40 km downstream from Hayes Volcano, reveal volcanic deposits that shed new light on its eruptive history. Three thick (>10 cm) and five thin (<10 cm) tephra-fall deposits are dacitic in whole rock composition and contain high proportions of amphibole to pyroxene and minor biotite and broadly correlate to Hayes tephra set H defined by earlier investigators. Two basal ages for the tephra-fall sequence of 3,690±30 and 3,750±30 14C yr B.P. are also consistent with the Hayes tephra set H timeframe. Distinguishing among Hayes tephra set H units is critical because the set is an important time-stratigraphic marker in south-central Alaska and this section provides a new reference section for Hayes tephra set H. Analysis of Fe-Ti oxide grains in the tephras shows promise for identifying individual Hayes deposits. Beneath the dacitic tephra sequence lies an older, poorly sorted tephra (tephra A) that contains dacite and rhyolite lapilli and whose basal age is 4,450±30 14C yr B.P. Immediately below the tephra-fall sequence (Unit III) lies a series of mass-flow deposits that are rich in rhyodacitic clasts (Unit II). Below Unit II and possibly coeval with it, is a 20–30 m thick pumiceous pyroclastic-flow deposit (Unit I) that extends to the valley floor. Here informally named the Hayes River ignimbrite, this deposit contains pumice clasts of rhyolite with quartz, sanidine, plagioclase, and biotite phenocrysts, an assemblage that is unique among known Quaternary volcanic products of Hayes and other Alaskan volcanoes. Units I, II, and tephra A of Unit III represent at least two previously unrecognized eruptions of Hayes Volcano that occurred prior to ~3,700 yr B.P. No compositionally equivalent distal tephra deposits correlative with Hayes Volcano rhyodacites or rhyolites have yet been identified, perhaps indicating that some of these deposits are pre-Holocene, and were largely removed by glacial ice during the last

  15. Part I: Neoacadian to Alleghanian foreland basin development and provenance in the central appalachian orogen, pine mountain thrust sheet Part II: Structural configuration of a modified Mesozoic to Cenozoic forearc basin system, south-central Alaska

    NASA Astrophysics Data System (ADS)

    Robertson, Peter Benjamin

    Foreland and forearc basins are large sediment repositories that form in response to tectonic loading and lithospheric flexure during orogenesis along convergent plate boundaries. In addition to their numerous valuable natural resources, these systems preserve important geologic information regarding the timing and intensity of deformation, uplift and erosion history, and subsidence history along collisional margins, and, in ancient systems, may provide more macroscopic information regarding climate, plate motion, and eustatic sea level fluctuations. This thesis presents two studies focused in the Paleozoic Appalachian foreland basin system along the eastern United States and in the Mesozoic to Cenozoic Matanuska forearc basin system in south-central Alaska. Strata of the Appalachian foreland basin system preserve the dynamic history of orogenesis and sediment dispersal along the east Laurentian margin, recording multiple episodes of deformation and basin development during Paleozoic time. A well-exposed, >600 m thick measured stratigraphic section of the Pine Mountain thrust sheet at Pound Gap, Kentucky affords one of the most complete exposures of Upper Devonian through Middle Pennsylvanian strata in the basin. These strata provide a window into which the foreland basin's development during two major collisional events known as the Acadian-Neoacadian and the Alleghanian orogenies can be observed. Lithofacies analysis of four major sedimentary successions observed in hanging wall strata record the upward transition from (1) a submarine deltaic fan complex developed on a distal to proximal prodelta in Late Devonian to Middle Mississippian time, to (2) a Middle to Late Mississippian carbonate bank system developed on a slowly subsiding, distal foreland ramp, which was drowned by (3) Late Mississippian renewed clastic influx to a tidally influenced, coastal deltaic complex to fluvial delta plain system unconformably overlain by (4) a fluvial braided river complex

  16. The Development of Three-Dimensional Gravity Inversion Software Applied to the Location and Geometry of the Border Ranges Fault System, South-Central Alaska

    NASA Astrophysics Data System (ADS)

    Cardenas, R.; Doser, D. I.; Mankhemthong, N.; Baker, M. R.

    2012-12-01

    Summary The Border Ranges Fault (BRFS) system bounds the Cook Inlet and Susitna Basins, an important petroleum province within south-central Alaska. The inversion utilizes gravity data constrained with geophysical, borehole, and surface geological information. The gravity inversion software was developed and tested by comparing and verifying several plausible structural models using several layers of geologic structure along the BRFS. The novel inversion approach involves directly modeling known geology, initially free-air corrected data, and revising a priori uncertainties on the geologic model to allow comparisons to alternative interpretations. Previous modeling of the BRFS using geophysical data has been limited due to the complexity of local geology and structure, both of shallow crustal features and the deeper subduction zone. Since this inversion is based on a sequence of gridded surfaces, it is feasible to develop software to help build these gridded geologic models. The gravity surveys are used in conjunction with known topology to create gridded surfaces. The software uses a Generalized, Nonlinear Least-Squares criterion to calculate the density solution of each gridded surface based on forward computations involving semi-infinite vertical line elements. The user has the capacity to observe the gravity misfit and make adjustments to the "a priori" information upon careful examination of each computed structural model. By varying several input parameters, the user can yield a range of plausible density models for making comparisons to several interpretations. Forward Model Computations The gravitational contributions are computed using a geophysics formulation, namely the vertical line element. g = πR2Gρ( x2 + y2 + z2)-1/2 Each line element is semi-infinite and extends from the top to the bottom of each structural layer. The contribution of the body to the gravity measurement will be computed as a volume integral and added to the overall contributions of

  17. Software Development for a Three-Dimensional Gravity Inversion and Application to Study of the Border Ranges Fault System, South-Central Alaska

    NASA Astrophysics Data System (ADS)

    Cardenas, R.; Doser, D. I.; Baker, M. R.

    2011-12-01

    Summary The Border Ranges Fault (BRFS) system bounds the Cook Inlet and Susitna Basins, an important petroleum province within south-central Alaska. An initial research goal is to test several plausible models of structure along the Border Ranges Fault System by developing a novel, 3D inversion software package. The inversion utilizes gravity data constrained with geophysical, borehole, and surface geological information. The novel inversion approach involves directly modeling known geology, initially free-air corrected data, and revising a priori uncertainties on the geologic model to allow comparisons to alternative interpretations. This technique to evaluate 3D structure in regions of highly complex geology can be applied in other studies of energy resources. The software reads an ASCII text file containing the latitude, longitude, elevation, and Free Air anomalies of each gravity station as well as gridded surface files of known topology. The contributions of each node in the grid are computed in order to compare the theoretical gravity calculations from a forward model to the gravity observations. The computation of solutions to the "linearized" inversion yields a range of plausible densities. The user will have the option of varying body proportions and dimensions to compare variations in density for changing depths of the gridded surface. Introduction Previous modeling of the BRFS using geophysical data has been limited due to the complexity of local geology and structure, both of shallow crustal features and the deeper subduction zone. Since the inversion is based on a sequence of gridded surfaces, it is feasible to develop software to help build these gridded geologic models. Without a way to modify grid surface elevations, density, and magnetic susceptibility in real time, the inversion process for the geologist would be highly nonlinear and poorly constrained, especially in structural geology this complex. Without a basic understanding of the geometry of

  18. Part I: Neoacadian to Alleghanian foreland basin development and provenance in the central appalachian orogen, pine mountain thrust sheet Part II: Structural configuration of a modified Mesozoic to Cenozoic forearc basin system, south-central Alaska

    NASA Astrophysics Data System (ADS)

    Robertson, Peter Benjamin

    Foreland and forearc basins are large sediment repositories that form in response to tectonic loading and lithospheric flexure during orogenesis along convergent plate boundaries. In addition to their numerous valuable natural resources, these systems preserve important geologic information regarding the timing and intensity of deformation, uplift and erosion history, and subsidence history along collisional margins, and, in ancient systems, may provide more macroscopic information regarding climate, plate motion, and eustatic sea level fluctuations. This thesis presents two studies focused in the Paleozoic Appalachian foreland basin system along the eastern United States and in the Mesozoic to Cenozoic Matanuska forearc basin system in south-central Alaska. Strata of the Appalachian foreland basin system preserve the dynamic history of orogenesis and sediment dispersal along the east Laurentian margin, recording multiple episodes of deformation and basin development during Paleozoic time. A well-exposed, >600 m thick measured stratigraphic section of the Pine Mountain thrust sheet at Pound Gap, Kentucky affords one of the most complete exposures of Upper Devonian through Middle Pennsylvanian strata in the basin. These strata provide a window into which the foreland basin's development during two major collisional events known as the Acadian-Neoacadian and the Alleghanian orogenies can be observed. Lithofacies analysis of four major sedimentary successions observed in hanging wall strata record the upward transition from (1) a submarine deltaic fan complex developed on a distal to proximal prodelta in Late Devonian to Middle Mississippian time, to (2) a Middle to Late Mississippian carbonate bank system developed on a slowly subsiding, distal foreland ramp, which was drowned by (3) Late Mississippian renewed clastic influx to a tidally influenced, coastal deltaic complex to fluvial delta plain system unconformably overlain by (4) a fluvial braided river complex

  19. Ordovician sponges from west-central and east-central Alaska and western Yukon Territory, Canada

    USGS Publications Warehouse

    Rigby, J.K.; Blodgett, R.B.; Britt, B.B.

    2008-01-01

    Moderate collections of fossil sponges have been recovered over a several-year period from a few scattered localities in west-central and east-central Alaska, and from westernmost Yukon Territory of Canada. Two fragments of the demosponge agelasiid cliefdenellid, Cliefdenella alaskaensis Stock, 1981, and mostly small unidentifiable additional fragments were recovered from a limestone debris flow bed in the White Mountain area, McGrath A-4 Quadrangle in west-central Alaska. Fragments of the agelasiid actinomorph girtyocoeliids Girtyocoeliana epiporata (Rigby & Potter, 1986) and Girtyocoelia minima n. sp., plus a specimen of the vaceletid colospongiid Corymbospongia amplia Rigby, Karl, Blodgett & Baichtal, 2005, were collected from probable Ashgillian age beds in the Livengood B-5 Quadrangle in east-central Alaska. A more extensive suite of corymbospongiids, including Corymbospongia betella Rigby, Potter & Blodgett, 1988, C. mica Rigby & Potter, 1986, and C.(?) perforata Rigby & Potter, 1986, along with the vaceletiid colospongiids Pseudo-imperatoria minima? (Rigby & Potter, 1986), and Pseudoimperatoria media (Rigby & Potter, 1986), and with the heteractinid Nucha naucum? Pickett & Jell, 1983, were recovered from uppermost part of the Jones Ridge Limestone (Ashgillian), on the south flank of Jones Ridge, in the Sheep Mountain Quadrangle, in westernmost Yukon Territory, Canada. The fossil sponges from the McGrath A-4 and Livengood B-5 quadrangles were recovered from attached Siberian terranes, and those from the Sheep Mountain Quadrangle were recovered from an allochthonous Laurentian terrane in the Yukon Territory.

  20. Placer tin deposits in central Alaska

    USGS Publications Warehouse

    Chapman, Robert Mills; Coats, Robert Roy; Payne, Thomas G.

    1963-01-01

    Placer tin, in the form of cassiterite (Sn02) and (or) tinstone (fragments including cassiterite and some vein or rock material), is known or reported in deposits that have been prospected or mined for placer gold in four areas adjacent to the Yukon River in central Alaska, 120 to 240 miles west of Fairbanks. These areas are: the Morelock Creek area, on the north side of the Yukon River about 30 miles upstream from Tanana; the Moran Dome area, about 16 miles north of the Yukon River and 25 miles northwest of Tanana; the Mason Creek area, on the north side of the Yukon River about 36 miles west of Tanana; and the Ruby-Long area, on the south side of the Yukon River near Ruby and about 40 miles east of Galena. The only extensive placer mining in these areas has been in the Ruby-Long area. Other placer deposits including some cassiterite are known in central Alaska but are not discussed in this report. Bedrock in these areas is predominantly schist of various types with some associated greenstone and other metamorphic rocks. Some granite is exposed in the Moran Dome and Ruby-Long areas and in areas close to Morelock and Mason Creeks. Barren, milky quartz veins and veinlets transecting the metamorphic rocks are common. No cassiterite was found in the bedrock, and no bedrock source of the tin has been reported. In the Moran Dome and Mason Creek areas, and in part of the Ruby-Long area, tourmaline is present in the rocks of the tin-bearing drainage basins, and apparently absent elsewhere in these areas. The placer deposits are in both valley floor and bench alluvium, which are predominantly relatively thin, rarely exceeding a thickness of 30 feet. Most of the alluvium deposits are not perennially frozen. In the Morelock Creek area tin-bearing deposits are 5 to 5? miles above the mouth of the creek, and meager evidence indicates that cassiterite and gold are present in Morelock Creek valley and some of the tributaries both upstream and downstream from these deposits. The

  1. 76 FR 45217 - Fisheries of the Exclusive Economic Zone Off Alaska; Central Gulf of Alaska Rockfish Program...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-28

    ... Economic Zone Off Alaska; Central Gulf of Alaska Rockfish Program; Amendment 88 AGENCY: National Marine... submitted Amendment 88 to the Fishery Management Plan for Groundfish of the Gulf of Alaska (FMP) for review... gains realized under the Rockfish Pilot Program and viability of the Gulf of Alaska fisheries....

  2. Structural evolution of the Port Wells gold mining district, Prince William Sound, south central Alaska: Implications for the origin of the gold lodes

    NASA Astrophysics Data System (ADS)

    Stuwe, K.

    1986-10-01

    Data collected in the Port Wells gold mining district, Alaska, indicate several stages in the structural history of the district. The first stage was the accretion and associated deformation of the Valdez group flysch sequence at the end of the Cretaceous. The deformation of the semilithified rocks included two folding phases forming isoclinal NE-SW-striking and SE-vergent folds during a D1 phase, and minor open warps in NW-SE direction during a D2 phase. Intrusion of early Oligocene (36 Ma) calc-alkaline granitoids followed deformation and was terminated by the emplacement of aplitic dikes. The major fracturing processes in both the granitoids and the country rocks occurred subsequently, probably during the uplift of the Chugach mountains in the late Tertiary. Several generations of epigenetic gold-bearing quartz veins were emplaced along the fractures at a later stage. Due to the significant time gap between peak metamorphism and mineralization, the metamorphic secretion model proposed for the vein formation is reconsidered.

  3. Stream-sediment samples reanalyzed for major, rare earth, and trace elements from seven 1:250,000-scale quadrangles, south-central Alaska, 2007-09

    USGS Publications Warehouse

    Gamble, Bruce M.; Bailey, Elizabeth A.; Shew, Nora B.; Labay, Keith A.; Schmidt, Jeanine M.; O'Leary, Richard M.; Detra, David E.

    2010-01-01

    During the 1960s through the 1980s, the U.S. Geological Survey conducted reconnaissance geochemical surveys of drainage basins throughout most of the Iliamna, Lake Clark, Lime Hills, and Talkeetna 1:250,000-scale quadrangles and parts of the McGrath, Seldovia, and Tyonek 1:250,000-scale quadrangles in Alaska. These geochemical surveys provide data necessary to assess the potential for undiscovered mineral resources and provide data that may be used to determine regional-scale element baselines. This report provides new data for 1,075 of the previously collected stream-sediment samples. The new analyses include a broader spectrum of elements and provide data that are more precise than the original analyses. All samples were analyzed for arsenic by hydride generation atomic absorption spectrometry, for gold, palladium, and platinum by inductively coupled plasma-mass spectrometry after lead button fire assay separation, and for a suite of 55 major, rare earth, and trace elements by inductively coupled plasma-atomic emission spectrometry and inductively coupled plasma-mass spectrometry after sodium peroxide sinter at 450 degrees Celsius.

  4. Relative sea-level response to Little Ice Age ice mass change in south central Alaska: Reconciling model predictions and geological evidence

    NASA Astrophysics Data System (ADS)

    Barlow, Natasha L. M.; Shennan, Ian; Long, Antony J.

    2012-01-01

    Integration of geological data and glacio-isostatic adjustment (GIA) modelling shows that it is possible to decouple complex mechanisms of relative sea-level (RSL) change in a tectonically active glacial environment. We model a simplest solution in which RSL changes in upper Cook Inlet, Alaska, are a combination of the interplay of tectonic and isostatic processes driven by the unique rheology of this tectonically active location. We calculate interseismic uplift during latter part of the penultimate earthquake cycle to vary from 0.3 to 0.7 mm/yr. Diatom based reconstructions of RSL from tidal marsh sediment sequences coupled with detailed age models, from AD 1400 to the AD 1964 great earthquake, show deviations from a purely tectonically driven model of regional RSL. Glacial isostatic modelling, constrained by GPS data, predicts up to 70 cm sea-level change due to mountain glacier mass balance changes during the Little Ice Age. Misfits between the GIA model predictions and RSL reconstructions in the 19th and 20th century highlight that the tidal marshes of upper Cook Inlet potentially record a hemispheric-wide acceleration in sea level and that other more complex Earth process combinations may contribute to regional RSL change.

  5. Insect-related tree mortality in south-central Alaska may be controlled by prior drought stress as indicated by δ13C and δ18O in tree rings

    NASA Astrophysics Data System (ADS)

    Miller, A. E.; Csank, A. Z.; Sherriff, R.; Berg, E.; Welker, J. M.

    2012-12-01

    Increasing temperatures at high latitudes have resulted in reduced growth and increased mortality across large areas of the northern boreal forest. A recent spruce beetle outbreak that killed over 1.5M ha of trees in south-central and southwest Alaska is thought to have been triggered by a series of warm summers that facilitated the accumulation of the beetle populations in already-physiologically stressed trees. Whether trees killed by the spruce beetle (Dendroctonus rufipennis) showed evidence of temperature-induced drought stress prior to death was examined by using tree-ring chronologies and δ13C & δ18O isotopic values in cellulose from paired live and dead trees at four sites in south-central Alaska. We also tested whether surviving trees differed from dead trees in their growth response and temperature sensitivity. Our results indicate that the trees killed by spruce beetle show reduced radial growth up to 20 years prior to death, relative to surviving trees, and that this is true across age and DBH classes (n=48 pairs; P<0.004). A moving correlation between June mean temperature and live and dead tree-growth indices from a mesic forest site shows that whereas growth in surviving trees was only weakly correlated with temperature until roughly 10 years before the beetle outbreak, growth in the dead trees was positively correlated with spring-summer temperatures, particularly June mean temperature (r=0.5; P<0.05) for several decades before. Approximately 10 years prior to tree death, growth in the dead trees became decoupled from temperature. This is in contrast to δ13C & δ18O values in dead trees from the site that show a strong positive correlation between δ13C and mean June maximum temperature (r2 = 0.35; P<0.001), and with δ18O later in the summer (June-July maximum temperature; r2 = 0.26; P<0.001). However, δ13C values showed a slightly higher correlation with spring temperatures (March-May average temperature; r2 = 0.36; P<0.001). In the 10 years

  6. Geochemical evidence for the origin of late Quaternary loess in central Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Budahn, J.R.

    2006-01-01

    Loess is extensive in central Alaska, but there are uncertainties about its source and the direction of paleo-winds that deposited it. Both northerly and southerly winds have been inferred. The most likely sources of loess are the Tanana River (south), the Nenana River (southeast), and the Yukon River (north). Late Quaternary loess in central Alaska has immobile trace-element compositions (Cr/Sc, Th/Ta, Th/ Sc, Th/U, Eu/Eu*, GdN/YbN) that indicate derivation mostly from the Tanana River. However, other ratios (As/Sb, Zr/Hf, LaN/YbN) and quantitative modeling indicate that the Yukon River was also a source. During the last glacial period, there may have been a longer residence time of the Siberian and Canadian high-pressure cells, along with a strengthened Aleutian low-pressure cell. This would have generated regional-scale northeasterly winds and explains derivation of loess from the Yukon River. However, superim-posed upon this synoptic-scale circulation, there may have been strong, southerly katabatic winds from expanded glaciers on the northern flank of the Alaska Range. These winds could have provided eolian silt from the Tanana River. Yukon River and Tanana River sediments are highly calcareous, whereas Fairbanks-area loess is not. This suggests that carbonate leaching in loess kept ahead of sedimentation and that late Quaternary loess in central Alaska was deposited relatively slowly. ?? 2006 NRC Canada.

  7. Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this spectacular MODIS image from November 7, 2001, the skies are clear over Alaska, revealing winter's advance. Perhaps the most interesting feature of the image is in its center; in blue against the rugged white backdrop of the Alaska Range, Denali, or Mt. McKinley, casts its massive shadow in the fading daylight. At 20,322 ft (6,194m), Denali is the highest point in North America. South of Denali, Cook Inlet appears flooded with sediment, turning the waters a muddy brown. To the east, where the Chugach Mountains meet the Gulf of Alaska, and to the west, across the Aleutian Range of the Alaska Peninsula, the bright blue and green swirls indicate populations of microscopic marine plants called phytoplankton. Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

  8. Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this spectacular MODIS image from November 7, 2001, the skies are clear over Alaska, revealing winter's advance. Perhaps the most interesting feature of the image is in its center; in blue against the rugged white backdrop of the Alaska Range, Denali, or Mt. McKinley, casts its massive shadow in the fading daylight. At 20,322 ft (6,194m), Denali is the highest point in North America. South of Denali, Cook Inlet appears flooded with sediment, turning the waters a muddy brown. To the east, where the Chugach Mountains meet the Gulf of Alaska, and to the west, across the Aleutian Range of the Alaska Peninsula, the bright blue and green swirls indicate populations of microscopic marine plants called phytoplankton.

  9. Deep-seated gravitational slope deformations near the Trans-Alaska Pipeline, east-central Alaska Range, Alaska, USA

    NASA Astrophysics Data System (ADS)

    Newman, S. D.; Clague, J. J.; Rabus, B.; Stead, D.

    2013-12-01

    Multiple, active, deep-seated gravitational slope deformations (DSGSD) are present near the Trans-Alaska Pipeline and Richardson Highway in the east-central Alaska Range, Alaska, USA. We documented spatial and temporal variations in rates of surface movement of the DSGSDs between 2003 and 2011 using RADARSAT-1 and RADARSAT-2 D-InSAR images. Deformation rates exceed 10 cm/month over very large areas (>1 km2) of many rock slopes. Recent climatic change and strong seismic shaking, especially during the 2002 M 7.9 Denali Fault earthquake, appear to have exacerbated slope deformation. We also mapped DSGSD geological and morphological characteristics using field- and GIS-based methods, and constructed a conceptual 2D distinct-element numerical model of one of the DSGSDs. Preliminary results indicate that large-scale buckling or kink-band slumping may be occurring. The DSGSDs are capable of generating long-runout landslides that might impact the Trans-Alaska Pipeline and Richardson Highway. They could also block tributary valleys, thereby impounding lakes that might drain suddenly. Wrapped 24-day RADARSAT-2 descending spotlight interferogram showing deformation north of Fels Glacier. The interferogram is partially transparent and is overlaid on a 2009 WorldView-1 panchromatic image. Acquisition interval: August 2 - August 26, 2011. UTM Zone 6N.

  10. Traces of Old Glaciations in East-central Alaska

    NASA Astrophysics Data System (ADS)

    Duk-Rodkin, A.; Barendregt, R. W.; Weber, F.

    2001-12-01

    The East-central Alaska record of glaciations is similar to that preserved in the west-central Yukon. Surficial geologic mapping of the Yukon-Tanana upland has indicated at least 5 glacial periods including at least one early Holocene. The two earliest glaciations are of pre-Mid Pleistocene age and followed regional erosion and renewed uplift ca.4 Ma. The earliest glaciation of west-central Yukon occurred between 2.6 and 2.9 Ma, forming a continuous carapace of ice covering all the mountain ranges except for a small part of the Dawson Range. This first glaciation was also the most extensive in the region, and resulted in the NW diversion of Yukon River into Alaska by the Cordilleran Ice Sheet. Stratigraphic evidence of 6 glaciations of pre-Mid Pleistocene age is preserved in the western Canadian sector of the Tintina Trench. The limits of these glaciations have been mapped in Yukon on the basis of glacial landforms and the distribution of erratics. Although morphological features of older glaciations (Plio-Pleistocene) are generally not well preserved, there is relatively good control on the distribution of glacial features for two of the older glaciations in Mt.Harper, Alaska. Stratigraphic evidence of at least 3 older glaciations is found in the Goodpastor River. An initial magnetostratigraphic study of three sites in east-central Alaska have yielded normal magnetic polarities only. The sites are:(1) a relatively weathered lowermost till outcropping along Goodpastor River on the Yukon-Tanana upland,(2) an extremely weathered high level moraine (609m) on the western side of the Gerstle River, near Granite Mt.in the Alaska Range and (3)ca.914m pediment containing glacial erratics and a luvisol at its surface, located on Tok River, Tanana Valley, Alaska Range. The normal polarity of the first site likely indicates a Brunhes age rather than a normal subchron within the Matuyama Reversed Chron based on the modest degree of weathering of the till and lack of any

  11. 75 FR 38452 - Fisheries of the Exclusive Economic Zone Off Alaska; Central Gulf of Alaska License Limitation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-02

    ... October 1, 1998 (63 FR 52642), and the LLP was implemented on January 1, 2000. The LLP for groundfish... Economic Zone Off Alaska; Central Gulf of Alaska License Limitation Program; Amendment 86 AGENCY: National... endorsement on licenses issued under the license limitation program (LLP) if those licenses have been used...

  12. 77 FR 50389 - Fisheries of the Exclusive Economic Zone Off Alaska; “Other Rockfish” in the Central Regulatory...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-21

    ... Economic Zone Off Alaska; ``Other Rockfish'' in the Central Regulatory Area of the Gulf of Alaska AGENCY... Central Regulatory Area of the Gulf of Alaska (GOA). This action is necessary because the 2012 total... Groundfish of the Gulf of Alaska (FMP) prepared by the North Pacific Fishery Management Council...

  13. Petrology of the Plutonic Rocks of west-central Alaska

    USGS Publications Warehouse

    Miller, Thomas P.

    1970-01-01

    A series of plutons in west-central Alaska defines the Hogatza plutonic belt which extends for about 200 miles in an east-west direction from the northeastern Seward Peninsula to the Koyukuk River. The plutonic rocks have an aggregate area of about 1,200 square miles and their composition, distribution, and possible petrogenesis are discussed for the first time in this report. Field, petrographic and chemical data supported by K/Ar age dating indicate the plutonic rocks are divisible into two suites differing in age, location, and composition. The western plutons are mid-Cretaceous (~100 m.y.) in age and consist of a heterogeneous assemblage of monzonite, syenite, quartz monzonite. Associated with these granitic rocks is a group of alkaline sub-silicic rocks that forma belt of intrusive complexes extending for a distance of at least 180 miles from west-central Alaska to the Bering Sea. The complex at Granite Mountain shows a rare example of zoning from an alkaline rim to a quartz-bearing core. The occurrence of a similar complex at Cape Dezhnev on the easternmost tip of Siberia suggests the alkaline province may extend into Siberia. The easternmost plutons are Late Cretaceous (180 m.y.) in age and composed primarily of granodiorite and quartz monzonite similar to calc-alkaline plutons found throughout the North America Cordillera. The plutons are epizonal and intrude deformed but unmetamorphosed Lower Cretaceous andesitic volcanics and volcanic graywacke which constitute the highly mobile Yukon-Koyukuk volcanogenic province of west-central Alaska. No older rocks have been found within the confines of this vast tract; the occurrence of a bounding ophiolite sequence has lead to the suggestion that the province was formed by large-scale rifting and is underlain by oceanic crust. The possibility of no juvenile sialic crust over much of the area suggests that the potassium-rich magma now represented by the alkaline rocks originated in the mantle. The distribution of the

  14. Reconstruction of recent climate change in Alaska from the Aurora Peak ice core, central Alaska

    NASA Astrophysics Data System (ADS)

    Tsushima, A.; Matoba, S.; Shiraiwa, T.; Okamoto, S.; Sasaki, H.; Solie, D. J.; Yoshikawa, K.

    2014-04-01

    A 180.17 m ice core was drilled at Aurora Peak in the central part of the Alaska Range, Alaska, in 2008 to allow reconstruction of centennial-scale climate change in the northern North Pacific. The 10 m-depth temperature in the borehole was -2.2 °C, which corresponded to annual mean air temperature at the drilling site. In this ice core, there were many melt-refrozen layers due to high temperature and/or strong insolation during summer seasons. We analyzed stable hydrogen isotopes (δD) and chemical species in the ice core. The ice core age was determined by annual counts of δD and seasonal cycles of Na+, and we used reference horizons of tritium peaks in 1963 and 1964, major volcanic eruptions of Mount Spurr in 1992 and Mount Katmai in 1912, and a large forest fire in 2004 as age controls. Here, we show that the chronology of the Aurora Peak ice core from 95.61 m w.eq. to the top corresponds to the period from 1900 to the summer season of 2008, with a dating error of ±3 years. We estimated that the mean accumulation rate from 1997 to 2007 (except for 2004) was 1.88 m w.eq per year. Our results suggest that temporal variation in δD and annual accumulation rates are strongly related to shifts in the Pacific Decadal Oscillation index (PDOI). The remarkable increase in annual precipitation since the 1970s has likely been the result of enhanced storm activity associated with shifts in the PDOI during winter in the Gulf of Alaska.

  15. Reconstruction of recent climate change in Alaska from the Aurora Peak ice core, central Alaska

    NASA Astrophysics Data System (ADS)

    Tsushima, A.; Matoba, S.; Shiraiwa, T.; Okamoto, S.; Sasaki, H.; Solie, D. J.; Yoshikawa, K.

    2015-02-01

    A 180.17 m ice core was drilled at Aurora Peak in the central part of the Alaska Range, Alaska, in 2008 to allow reconstruction of centennial-scale climate change in the northern North Pacific. The 10 m depth temperature in the borehole was -2.2 °C, which corresponded to the annual mean air temperature at the drilling site. In this ice core, there were many melt-refreeze layers due to high temperature and/or strong insolation during summer seasons. We analyzed stable hydrogen isotopes (δD) and chemical species in the ice core. The ice core age was determined by annual counts of δD and seasonal cycles of Na+, and we used reference horizons of tritium peaks in 1963 and 1964, major volcanic eruptions of Mount Spurr in 1992 and Mount Katmai in 1912, and a large forest fire in 2004 as age controls. Here, we show that the chronology of the Aurora Peak ice core from 95.61 m to the top corresponds to the period from 1900 to the summer season of 2008, with a dating error of ± 3 years. We estimated that the mean accumulation rate from 1997 to 2007 (except for 2004) was 2.04 m w.eq. yr-1. Our results suggest that temporal variations in δD and annual accumulation rates are strongly related to shifts in the Pacific Decadal Oscillation index (PDOI). The remarkable increase in annual precipitation since the 1970s has likely been the result of enhanced storm activity associated with shifts in the PDOI during winter in the Gulf of Alaska.

  16. South Central California Coastline and Channel Islands

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This distant and very oblique image of the south Central California Coastline and Channel Islands (35.0N, 119.0W) offers a spectacular and scenic view of the southern west coast, the central San Joaquin Valley, the entire Sierra Nevada Range and across the southwest to the Rocky Mountains on the horizon.

  17. Character, distribution, and tectonic significance of accretionary terranes in the Central Alaska Range

    NASA Astrophysics Data System (ADS)

    Jones, David L.; Silberling, N. J.; Gilbert, Wyatt; Coney, Peter

    1982-05-01

    The central part of the Alaska Range near Mount McKinley is composed of nine separate tectonostratigraphic terranes that were accreted in southern Alaska during late Mesozoic time. These terranes now form long, linear, fault-bounded belts that are subparallel to the Denali fault on the north but oblique to the fault on the south. The postaccretion right lateral offset along the Denali fault system is about 200 km. From north to south the major terranes are (1) Yukon-Tanana terrane, metasedimentary and metavolcanic rocks, mostly undated, but including rocks of known late Paleozoic age; polymetamorphosed with terminal events in late Mesozoic, (2) Pingston terrane, isoclinally folded Upper Triassic deep-water silty limestone, quartzite, and carbonaceous slate, folded with upper Paleozoic phyllite, chert, tuff, and minor limestone, (3) McKinley terrane, upper Paleozoic flysch, chert, and minor limestone, intruded by large gabbro sills and dikes and overlain by thick piles of Triassic porphyritic pillow lava; the top of the section is thick sequence of upper Mesozoic conglomerate, flysch, chert, and phyllite, (4) Dillinger terrane, very thick sequence of strongly folded lower Paleozoic micaceous sandstone (turbidites), graptolitic shale, and deep-water limestone, locally overlain unconformably by Jurassic fossiliferous sandstone or Triassic (?) pillow basalt, (5) Windy terrane, heterogeneous assemblage of serpentinite, basalt, tuff, and chert (= ophiolite?) with Paleozoic and Mesozoic flysch and blocks of mid-Paleozoic fossiliferous limestone, (6) Mystic terrane, predominantly upper Paleozoic flysch and conglomerate, but also includes lower Paleozoic graptolitic shale, pillow basalt, and shallow-water limestone, and upper Paleozoic fossiliferous limestone, sandstone, chert, and undated pillow basalt, (7) Chulitna terrane, Upper Devonian ophiolite overlain by upper Paleozoic chert, volcanic conglomerate, limestone, and flysch, capped by Lower Triassic limestone and Upper

  18. Block rotation in east-central Alaska: a framework for evaluating earthquake potential?

    USGS Publications Warehouse

    Page, R.A.; Plafker, G.; Pulpan, H.

    1995-01-01

    Geologic and seismic data reveal a set of parallel, active, strike-slip faults in east-central Alaska between the Denali and Tintina fault systems. The faults strike northeast to north-northeast, at a high angle to the bounding dextral fault systems, and exhibit sinistral slip. This hypothesizes that this set of faults divides the crust into long blocks that are rotating clockwise in response to northerly compression resulting from Pacific-North American plate convergence. It is suggested that these faults have produced most of the large historical earthquakes in east-central Alaska between the Alaska Range and the Yukon River. -Authors

  19. Floods of August 1967 in east-central Alaska

    USGS Publications Warehouse

    Childers, Joseph M.; Meckel, James P.; Anderson, Gary S.

    1972-01-01

    East-central Alaska had record floods near Fairbanks following extensive rains of August 8-20, 1967. Precipitation during this period totaled as much as 10 inches, which is close to the average annual precipitation for this area. The most extensive flooding occurred in the White Mountains northeast of Fairbanks and along the major streams draining those mountains. Some of the major streams flooded were the Salcha, Chena, Chatanika, Tolovana, and lower Tanana Rivers, and Birch Creek west of Circle. Peak discharges on some streams in the flood area were from two to four times the probable 50-year flood. The peak discharge of 74,400 cubic feet per second of the Chena River at Fairbanks, from 1,980 square miles of drainage area, was 2.6 times the 50-year flood. The rise of ground-water levels in the Tanana River flood plain to the land surface during the flood caused foundation failures and prevented drainage of subsurface structures. Above-normal ground-water levels existed until the middle of September. Total flood damage was estimated in excess of $85 million. Six lives were reported lost, and about 12,000 persons were evacuated during the flood. This report has been prepared to furnish hydrologic data for development planning. Included are discussions of antecedent streamflow, meteorology of the storm, descriptions of floods, flood damage, flood frequency, ground-water conditions, and stages and discharges of major streams for August 1967.

  20. 78 FR 14076 - Fisheries of the Exclusive Economic Zone Off Alaska; Groundfish of the Gulf of Alaska; Central...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-04

    ...NMFS publishes the standard ex-vessel prices and fee percentage for cost recovery under the Central Gulf of Alaska Rockfish Program. This action is intended to provide participants in a rockfish cooperative with the standard prices and fee percentage for the 2012 fishing year, which was authorized from May 1 through November 15. The fee percentage is 1.4 percent. The fee liability payments......

  1. Geologic map of the Big Delta B-2 quadrangle, east-central Alaska

    USGS Publications Warehouse

    Day, Warren C.; Aleinikoff, John N.; Roberts, Paul; Smith, Moira; Gamble, Bruce M.; Henning, Mitchell W.; Gough, Larry P.; Morath, Laurie C.

    2003-01-01

    New 1:63,360-scale geologic mapping of the Big Delta B-2 quadrangle provides important data on the structural setting and age of geologic units, as well as on the timing of gold mineralization plutonism within the Yukon-Tanana Upland of east-central Alaska. Gold exploration has remained active throughout the region in response to the discovery of the Pogo gold deposit, which lies within the northwestern part of the quadrangle near the south bank of the Goodpaster River. Geologic mapping and associated geochronological and geochemical studies by the U.S. Geological Survey (USGS) and the Alaska Department of Natural Resources, Division of Mining and Water Management, provide baseline data to help understand the regional geologic framework. Teck Cominco Limited geologists have provided the geologic mapping for the area that overlies the Pogo gold deposit as well as logistical support, which has lead to a much improved and informative product. The Yukon-Tanana Upland lies within the Tintina province in Alaska and consists of Paleozoic and possibly older(?) supracrustal rocks intruded by Paleozoic (Devonian to Mississippian) and Cretaceous plutons. The oldest rocks in the Big Delta B-2 quadrangle are Paleozoic gneisses of both plutonic and sedimentary origin. Paleozoic deformation, potentially associated with plutonism, was obscured by intense Mesozoic deformation and metamorphism. At least some of the rocks in the quadrangle underwent tectonism during the Middle Jurassic (about 188 Ma), and were subsequently deformed in an Early Cretaceous contractional event between about 130 and 116 Ma. New U-Pb SHRIMP data presented here on zircons from the Paleozoic biotite gneisses record inherited cores that range from 363 Ma to about 2,130 Ma and have rims of euhedral Early Cretaceous metamorphic overgrowths (116 +/- 4 Ma), interpreted to record recrystallization during Cretaceous west-northwest-directed thrusting and folding. U-Pb SHRIMP dating of monazite from a Paleozoic

  2. 7. INTERIOR, KITCHEN SOUTH OF CENTRAL EASTWEST CORRIDOR, FROM ENTRY, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. INTERIOR, KITCHEN SOUTH OF CENTRAL EAST-WEST CORRIDOR, FROM ENTRY, LOOKING SOUTH. - Oakland Naval Supply Center, Administration Building-Dental Annex-Dispensary, Between E & F Streets, East of Third Street, Oakland, Alameda County, CA

  3. OVERALL VIEW OF CEMETERY SECTIONS SOUTH OF CENTRAL DRIVE, SHOWING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    OVERALL VIEW OF CEMETERY SECTIONS SOUTH OF CENTRAL DRIVE, SHOWING SECTION MARKER AT BASE OF TREE. VIEW TO SOUTH. - Baton Rouge National Cemetery, 220 North 19th Street, Baton Rouge, East Baton Rouge Parish, LA

  4. OVERALL VIEW OF CEMETERY SECTIONS SOUTH OF CENTRAL DRIVE, WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    OVERALL VIEW OF CEMETERY SECTIONS SOUTH OF CENTRAL DRIVE, WITH PERIMETER FENCE IN BACKGROUND. VIEW TO SOUTH. - Baton Rouge National Cemetery, 220 North 19th Street, Baton Rouge, East Baton Rouge Parish, LA

  5. 8. VIEW LOOKING SOUTH, SHOWING NORTH ENTRANCE HOUSE AND CENTRAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    8. VIEW LOOKING SOUTH, SHOWING NORTH ENTRANCE HOUSE AND CENTRAL PAVILION, WITH SOUTH ENTRANCE HOUSE AND ENGINE HOUSE BEYOND - Fairmount Waterworks, East bank of Schuylkill River, Aquarium Drive, Philadelphia, Philadelphia County, PA

  6. Break-up characteristics of the Chena River watershed, central Alaska

    NASA Technical Reports Server (NTRS)

    Carlson, R. F. (Principal Investigator); Wendler, G.; Kane, D. L.

    1973-01-01

    The author has identified the following significant results. The snow melt for a small watershed (5130 sq km) in Central Alaska was successfully monitored with ERTS-1 imagery. Aerial photography was used as supporting data for periods without satellite coverage. Comparison both with actual measurements and with a computer model showed good agreement.

  7. Radioactivity at the Copper Creek copper lode prospect, Eagle district, east-central Alaska

    USGS Publications Warehouse

    Wedow, Helmuth; Tolbert, Gene Edward

    1952-01-01

    Investigation of radioactivity anomalies at the Copper Creek copper lode prospect, Eagle district, east-central Alaska, during 1949 disclosed that the radioactivity is associated with copper mineralization in highly metamorphosed sedimentary rocks. These rocks are a roof pendant in the Mesozoic "Charley River" batholith. The radioactivity is probably all due to uranium associated with bornite and malachite.

  8. 29. INTERIOR VIEW OF FERRY MOUSE, SOUTH CENTRAL BUILDING, FIRST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. INTERIOR VIEW OF FERRY MOUSE, SOUTH CENTRAL BUILDING, FIRST LEVEL, LOOKING WEST, FERRYMEN'S QUARTERS - Central Railroad of New Jersey, Jersey City Ferry Terminal, Johnson Avenue at Hudson River, Jersey City, Hudson County, NJ

  9. Tertiary tectonics of the Border Ranges Fault system, north-central Chugach Mountains, Alaska: Sedimentation, deformation and uplift along the inboard edge of a subduction complex

    SciTech Connect

    Little, T.A.

    1988-01-01

    In south-central Alaska the Border Ranges Fault system (BRFS) separates lower Paleogene rocks of a forearc basin sequence from a Cretaceous subduction complex. In a north-central part of the Chugach Mountains the upper Paleocene-lower Eocene Chickaloon Formation was deposited along the seaward margin of the forearc basin as an alluvial fan complex. A field study combining geologic mapping of a {approximately}200 km{sup 2} region, stratigraphic studies, K-Ar and fission-track geochronology, metamorphic petrology, and detailed structural analysis of deformed rocks on both sides of the BRFS has been used to reconstruct the Tertiary history of displacements and uplift events along the inboard edge of Alaska's subduction-accretion complex.

  10. 150,000 years of loess accumulation in central Alaska

    NASA Astrophysics Data System (ADS)

    Jensen, Britta J. L.; Evans, Michael E.; Froese, Duane G.; Kravchinsky, Vadim A.

    2016-03-01

    The Halfway House site in interior Alaska is arguably the most studied loess deposit in northwestern North America. The site contains a complex paleomagnetic and paleoenvironmental record, but has lacked the robust chronologic control that would allow its full potential to be exploited. Detailed reexamination of stratigraphy, paleomagnetics and tephrostratigraphy reveals a relatively complete marine isotope stage (MIS) 6 to Holocene record constrained by the Old Crow (124 ± 10 ka), VT (106 ± 10 ka), Sheep Creek-Klondike (ca. 80 ka), Dominion Creek (77 ± 8 ka) and Dawson (ca. 30.2 cal ka BP) tephras. We show two well-developed paleosols formed during Marine Isotope Stages (MIS) 5e and 5a, while MIS 5c and 5b are either poorly represented or absent. The new tephrostratigraphy presented here is the most complete one to date for the late Pleistocene and indicates MIS 5 sediments are more common than previously recognized. A magnetic excursion within the sediments is identified as the post-Blake excursion (94.1 ± 7.8 ka), providing independent age control and adding to the increasing body of evidence that Alaskan loess is a detailed recorder of variations of the Earth's magnetic field over time. A high-resolution magnetic susceptibility profile placed into this new chronostratigraphic framework supports the hypothesis that wind-intensity is the main variable controlling fluctuations in susceptibility. Correlation of the susceptibility record to global marine δ18O records is complicated by highly variable accumulation rates. We find the lowest rates of accumulation during peak warm and cold stages, while abrupt increases are associated with periods of transition between marine isotope (sub)stages. Building on previous accumulation models for Alaska, surface roughness is likely a leading variable controlling loess accumulation rates during transitions and peak cold periods, but the negligible accumulation during MIS 5e and 5a suggests that loess production was

  11. Structural architecture of the central Brooks Range foothills, Alaska

    USGS Publications Warehouse

    Moore, Thomas E.; Potter, Christopher J.; O'Sullivan, Paul B.

    2002-01-01

    Five structural levels underlie the Brooks Range foothills, from lowest to highest: (1) autochthon, at a depth of ~9 km; (2) Endicott Mountains allochthon (EMA), thickest under the northern Brooks Range (>15 km) and wedging out northward above the autochthon; (3) higher allochthons (HA), with a composite thickness of 1.5+ km, wedging out northward at or beyond the termination of EMA; (4) Aptian-Albian Fortress Mountain Formation (FM), deposited unconformably on deformed EMA and HA and thickening northward into a >7-km-thick succession of deformed turbidites (Torok Formation); (5) gently folded Albian-Cenomanian deltaic deposits (Nanushuk Group). The dominant faulting pattern in levels 2-3 is thin-skinned thrusting and thrust-related folds formed before deposition of Cretaceous strata. These structures are cut by younger steeply south-dipping reverse faults that truncate and juxtapose structural levels 1-4 and expose progressively deeper structural levels to the south. Structural levels 4-5 are juxtaposed along a north-dipping zone of south-vergent folds and thrusts. Stratigraphic and fission-track age data suggest a kinematic model wherein the foothills belt was formed first, by thrusting of HA and EMA as deformational wedges onto the regionally south-dipping authochon at 140-120Ma. After deposition of FM and Torok during mid-Cretaceous hinterland extension and uplift, a second episode of contractional deformation at 60 Ma shortened the older allochthonous deformational wedges (EMA, HA) and overlying strata on north-vergent reverse faults. To the north, where the allochthons wedge out, shortening caused duplexing in the Torok and development of a triangle zone south of the Tuktu escarpment.

  12. Seasonal Variability of South Atlantic Central Water

    NASA Astrophysics Data System (ADS)

    Nobrega Passos, E.; de Freitas Assad, L.; Landau, L.

    2013-05-01

    The South Atlantic Ocean (SAO) is constituted by different density water masses. Among these, the South Atlantic Central Water (SACW) is formed on the Brazil-Falkland Confluence region (BFC) and once formed, it becomes part of the Subtropical Gyre. When approaching again the Brazilian coast, this water mass bifurcates next to São Tomé Cape and part of it flows to the North and part to the South. There is another bifurcation that formed the sub-gyre of the SAO and occurs near 30°S. This work aims to analyze the seasonal variability associated to the SACW trajectory on the SAO basin. To achieve this goal, ECCO2 project's time series of prognostic fields were analysed. The parameters evaluated were temperature, salinity and the zonal and meridional velocity components in averaged monthly fields between January 1992 and November 2010. First a climatological year was calculated and was composed by means from all time series for each month. And second, it was estimate seasonally means for the south hemisphere to summer, autumn, winter and springer. For the analysis, the SACW was separated from the rest of the water masses by isolating it for its temperature, salinity and density index. Then the volume transport (VT) was calculated for seven different sections: A (10°S and 36°W-30°W), B (35°S and 55°W-45°W), C (40°W and 37°S-43°S), D (34°S and 7°E-20°E), E (20°E and 34°S-45°S), F (20°W and 27°S-33°S) and G (10°W and 20°S-25°S). The VT integrated on the water column occupied by SACW was calculated from the zonal and meridional velocities. The analysis showed that the VT balance between the sections is consistent with the climatologic analysis, according to scientific references. The analysis of the climatological VT showed that the VT field integrated in SAWC levels is also consistent with scientific reference. On the seasonal analysis, the sections A and F show a stronger VT during autumn. Since section A is formed from part of the flux of section

  13. Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Though it's not quite spring, waters in the Gulf of Alaska (right) appear to be blooming with plant life in this true-color MODIS image from March 4, 2002. East of the Alaska Peninsula (bottom center), blue-green swirls surround Kodiak Island. These colors are the result of light reflecting off chlorophyll and other pigments in tiny marine plants called phytoplankton. The bloom extends southward and clear dividing line can be seen west to east, where the bloom disappears over the deeper waters of the Aleutian Trench. North in Cook Inlet, large amounts of red clay sediment are turning the water brown. To the east, more colorful swirls stretch out from Prince William Sound, and may be a mixture of clay sediment from the Copper River and phytoplankton. Arcing across the top left of the image, the snow-covered Brooks Range towers over Alaska's North Slope. Frozen rivers trace white ribbons across the winter landscape. The mighty Yukon River traverses the entire state, beginning at the right edge of the image (a little way down from the top) running all the way over to the Bering Sea, still locked in ice. In the high-resolution image, the circular, snow-filled calderas of two volcanoes are apparent along the Alaska Peninsula. In Bristol Bay (to the west of the Peninsula) and in a couple of the semi-clear areas in the Bering Sea, it appears that there may be an ice algae bloom along the sharp ice edge (see high resolution image for better details). Ground-based observations from the area have revealed that an under-ice bloom often starts as early as February in this region and then seeds the more typical spring bloom later in the season.

  14. Limits to northward drift of the Paleocene Cantwell Formation, central Alaska.

    USGS Publications Warehouse

    Hillhouse, J.W.; Gromme, C.S.

    1982-01-01

    Volcanic rocks of the Paleocene Cantwell Formation in central Alaska apparently originated at a paleolatitude of 83oN (alpha 95 = 9.7o), as indicated by paleomagnetic results. When compared with the Paleocene pole for the North American craton, the 95% confidence limits of the results suggest that terranes N of the Denali fault have moved no more than 550km northward relative to the North American craton since Paleocene time.-Authors

  15. Holocene loess and paleosols in central Alaska: A proxy record of Holocene climate change

    SciTech Connect

    Bigelow, N.H.; Beget, J.E.

    1992-03-01

    Episodic Holocene loess deposition and soil formation in the sediments of the Nenana valley of Central Alaska may reflect Holocene climate change. Periods of loess deposition seem to correlate with times of alpine glacier activity, while paleosols correspond to times of glacial retreat These variations may reflect changes in solar activity Stuiver and Braziunas, 1989. Other mechanisms, such as orbitally forced changes in seasonality, volcanism, and atmospheric C02 variability may also have affected Holocene climates and loess deposition.

  16. OVERALL VIEW OF CEMETERY SECTIONS SOUTH OF CENTRAL DRIVE, WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    OVERALL VIEW OF CEMETERY SECTIONS SOUTH OF CENTRAL DRIVE, WITH LODGE BUILDING AT CENTER BACKGROUND. VIEW TO NORTHWEST. - Baton Rouge National Cemetery, 220 North 19th Street, Baton Rouge, East Baton Rouge Parish, LA

  17. 88. 451 MADISON AVENUE, LIBRARY, SOUTH WALL, WEST CENTRAL SECTION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    88. 451 MADISON AVENUE, LIBRARY, SOUTH WALL, WEST CENTRAL SECTION SHOWING WINDOW AND RADIATOR (Pair with NY-5635-89) - Villard Houses, 451-457 Madison Avenue & 24 East Fifty-first Street, New York County, NY

  18. 14. INTERIOR CENTRAL STAIRWAY, FIRST FLOOR LOOKING SOUTH NEWEL POSTS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. INTERIOR CENTRAL STAIRWAY, FIRST FLOOR LOOKING SOUTH NEWEL POSTS WITH LIGHTS - Louisana State Capitol, North Boulevard, Saint Philip, America & Front Streets, Baton Rouge, East Baton Rouge Parish, LA

  19. PERSPECTIVE VIEW OF CENTRAL BAY OF EAST ARMORY, LOOKING SOUTH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    PERSPECTIVE VIEW OF CENTRAL BAY OF EAST ARMORY, LOOKING SOUTH SOUTHEAST. - Colt Fire Arms Company, East Armory Building, 36-150 Huyshope Avenue, 17-170 Van Dyke Avenue, 49 Vredendale Avenue, Hartford, Hartford County, CT

  20. 1. Ice Plant, south facade, two central bays. On the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. Ice Plant, south facade, two central bays. On the right, the Creamery; to the left, loading dock of Hay and Grain Warehouse. - Curtis Wharf, Ice Plant, O & Second Streets, Anacortes, Skagit County, WA

  1. Central portion of front (south side) from west parking area ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Central portion of front (south side) from west parking area - Fitzsimons General Hospital, Main Hospital Building, Charlie Kelly Boulevard, North side, at intersection of Sharon A. Lane Drive, Aurora, Adams County, CO

  2. Central tower of the front ( south side) with the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Central tower of the front ( south side) with the top of the porte cochere in the foreground - Fitzsimons General Hospital, Main Hospital Building, Charlie Kelly Boulevard, North side, at intersection of Sharon A. Lane Drive, Aurora, Adams County, CO

  3. Interior view, groundfloor passage in central pavilion, looking south. The ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Interior view, ground-floor passage in central pavilion, looking south. The forward opening accesses the elevator shaft. The well articulated doorway behind lets onto a small vestibule located on the west ground floor Verandah of the south wing. - U. S. Naval Asylum, Biddle Hall, Gray's Ferry Avenue, Philadelphia, Philadelphia County, PA

  4. 6. CENTRAL PORTION OF SOUTH SIDE OF BUILDING, FROM PARKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. CENTRAL PORTION OF SOUTH SIDE OF BUILDING, FROM PARKING LOT NORTH OF BERTH B-1 (WESTERN END OF G STREET), LOOKING NORTHEAST, WITH BUILDING 123 AT FAR RIGHT. - Oakland Naval Supply Center, Pier Transit Shed, South of D Street between First & Second Streets, Oakland, Alameda County, CA

  5. Central tower section of the front (south side) with the ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Central tower section of the front (south side) with the top of the central entrance projection at the bottom - Fitzsimons General Hospital, Main Hospital Building, Charlie Kelly Boulevard, North side, at intersection of Sharon A. Lane Drive, Aurora, Adams County, CO

  6. Ophiolitic terranes of northern and central Alaska and their correlatives in Canada and northeastern Russia

    SciTech Connect

    Patton, W.W. Jr. )

    1993-04-01

    All of the major ophiolitic terranes (Angayucham, Tozitna, Innoko, Seventymile, and Goodnews terranes) in the northern and central Alaska belong to the Tethyan-type' of Moores (1982) and were obducted onto Paleozoic and Proterozoic continental and continental margin terranes in Mesozoic time. Tethyan-type' ophiolitic assemblages also occur in the Slide Mountain terrane in the Canadian Cordillera and extend from western Alaska into northeastern Russia. Although investigators have suggested widely different ages from their times of abduction onto the continent, these ophiolitic terranes display some remarkably similar features: (1) they consist of a stack of imbricated thrust slices dominated by ocean floor sediments, basalt, and high-level gabbro of late Paleozoic and Triassic age; (2) their mafic-ultramafic complexes generally are confined to the uppermost thrust sheets; (3) they lack the large tectonic melanges zones and younger accretionary flysch deposits associated with the ophiolitic terranes of southern Alaska and the Koryak region of northeastern Russia; (4) blueschist mineral assemblages occur in the lower part of these ophiolite terranes and (or) in the underlying continental terranes; and (5) they are bordered on their outboard' side by Mesozoic intraoceanic volcanic arc terranes. Recent geochemical and geologic studies of the mafic-ultramafic complexes in the Anagayucham and Tozitna terranes strongly suggest they were generated in a supra-subduction zone (SSZ) and that they are directly overlain by volcanic rocks of the Koyukuk terrane.

  7. 77 FR 75399 - Fisheries of the Exclusive Economic Zone Off Alaska; Big Skate in the Central Regulatory Area of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-20

    ...NMFS is prohibiting retention of big skate in the Central Regulatory Area of the Gulf of Alaska (GOA). This action is necessary because the 2012 total allowable catch of big skate in the Central Regulatory Area of the GOA has been...

  8. 78 FR 27863 - Fisheries of the Exclusive Economic Zone Off Alaska; Big Skate in the Central Regulatory Area of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-13

    ...NMFS is prohibiting retention of big skate in the Central Regulatory Area of the Gulf of Alaska (GOA). This action is necessary because the 2013 total allowable catch of big skate in the Central Regulatory Area of the GOA has been...

  9. 75 FR 69601 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Ocean Perch in the Central Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-15

    ... Economic Zone Off Alaska; Pacific Ocean Perch in the Central Aleutian District of the Bering Sea and... directed fishing for Pacific ocean perch in the Central Aleutian District of the Bering Sea and Aleutian... action is necessary to prevent exceeding the 2010 allocation of Pacific ocean perch in this...

  10. 77 FR 39440 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Ocean Perch in the Central Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ... Economic Zone Off Alaska; Pacific Ocean Perch in the Central Aleutian District of the Bering Sea and... directed fishing for Pacific ocean perch in the Central Aleutian District of the Bering Sea and Aleutian... action is necessary to prevent exceeding the 2012 allocation of Pacific ocean perch in this...

  11. Late Pliocene to late Pleistocene environments preserved at the Palisades Site, central Yukon River, Alaska

    NASA Astrophysics Data System (ADS)

    Matheus, Paul; Begét, James; Mason, Owen; Gelvin-Reymiller, Carol

    2003-07-01

    The Palisades Site is an extensive silt-loam bluff complex on the central Yukon River preserving a nearly continuous record of the last 2 myr. Volcanic ash deposits present include the Old Crow (OCt; 140,000 yr), Sheep Creek (SCt; 190,000 yr), PA (2.02 myr), EC (ca. 2 myr), and Mining Camp (ca. 2 myr) tephras. Two new tephras, PAL and PAU, are geochemically similar to the PA and EC tephras and appear to be comagmatic. The PA tephra occurs in ice-wedge casts and solifluction deposits, marking the oldest occurrence of permafrost in central Alaska. Three buried forest horizons are present in association with dated tephras. The uppermost forest bed occurs immediately above the OCt; the middle forest horizon occurs below the SCt. The lowest forest bed occurs between the EC and the PA tephras, and correlates with the Dawson Cut Forest Bed. Plant taxa in all three peats are common elements of moist taiga forest found in lowlands of central Alaska today. Large mammal fossils are all from common late Pleistocene taxa. Those recovered in situ came from a single horizon radiocarbon dated to ca. 27,000 14C yr B.P. The incongruous small mammal assemblage in that horizon reflects a diverse landscape with both wet and mesic environments.

  12. Neogene transpressional foreland basin development on the north side of the central alaska range, usibelli group and nenana gravel, tanana basin

    USGS Publications Warehouse

    Ridgway, K.D.; Thoms, E.E.; Layer, P.W.; Lesh, M.E.; White, J.M.; Smith, S.V.

    2007-01-01

    Neogene strata of the Tanana basin provide a long-term record of a northwardpropagating, transpressional foreland-basin system related to regional shortening of the central Alaska Range and strike-slip displacement on the Denali fault system. These strata are ???2 km thick and have been deformed and exhumed in thrust faults that form the foothills on the north side of the Alaska Range. The lower part of the sedimentary package, the Usibelli Group, consists of 800 m of mainly Miocene strata that were deposited in fluvial, lacustrine, and peat bog environments of the foredeep depozone of the foreland-basin system. Compositional data from conglomerate and sandstone, as well as recycled Upper Cretaceous palynomorphs, indicate that the Miocene foreland-basin system was supplied increasing amounts of sediment from lithologies currently exposed in thrust sheets located south of the basin. The upper part of the sedimentary package, the Nenana Gravel, consists of 1200 m of mainly Pliocene strata that were deposited in alluvial-fan and braidplain environments in the wedge-top depozone of the foreland-basin system. Compositional data from conglomerate and sandstone, as well as 40Ar/39Ar dating of detrital feldspars in sandstone and from granitic clasts in conglomerate, indicate that lithologies exposed in the central Alaska Range provided most of the detritus to the Pliocene foreland-basin system. 40Ar/39Ar dates from detrital feldspar grains also show that two main suites of plutons contributed sediment to the Nenana Gravel. Detrital feldspars with an average age of 56 Ma are interpreted to have been derived from the McKinley sequence of plutons located south of the Denali fault. Detrital feldspars with an average age of 34 Ma are interpreted to have been derived from plutons located north of the Denali fault. Plutons located south of the Denali fault provided detritus for the lower part of the Nenana Gravel, whereas plutons located north of the Denali fault began to

  13. Assessment of undiscovered petroleum resources in Central and South America

    USGS Publications Warehouse

    Schenk, C.J.

    2002-01-01

    The USGS has assessed undiscovered conventional oil and gas resources in 128 selected petroleum provinces of the world. Of these 128 provinces, 23 are in South America, Central America, and the Caribbean area. In the USGS 2000 Assessment, the provinces resulted in mean totals for undiscovered resource of 105 billion bbl of oil and 487 tcf of gas. The potential for giant oil and gas fields is greatest in the basins along the Atlantic margin of eastern South America, from the Santos Basin in the south to the Guyana-Suriname Basin in the north. The potential for giant fields is mainly offshore, in water depths up to 3600 m. The South and Central America region ranks third in the world for undiscovered conventional oil and gas behind the Middle East and the Former Soviet Union.

  14. Regional Geochemical Results from the Reanalysis of NURE Stream Sediment Samples - Eagle 3? Quadrangle, East-Central Alaska

    USGS Publications Warehouse

    Crock, J.G.; Briggs, P.H.; Gough, L.P.; Wanty, R.B.; Brown, Z.A.

    2007-01-01

    This report presents reconnaissance geochemical data for a cooperative study in the Fortymile Mining District, east-central Alaska, initiated in 1997. This study has been funded by the U.S. Geological Survey (USGS) Mineral Resources Program. Cooperative funds were provided from various State of Alaska sources through the Alaska Department of Natural Resources. Results presented here represent the initial reconnaissance phase for this multidisciplinary cooperative study. In this phase, 239 sediment samples from the Eagle 3? Quadrangle of east-central Alaska, which had been collected and analyzed for the U.S. Department of Energy's National Uranium Resource Evaluation program (NURE) of the 1970's (Hoffman and Buttleman, 1996; Smith, 1997), are reanalyzed by newer analytical methods that are more sensitive, accurate, and precise (Arbogast, 1996; Taggart, 2002). The main objectives for the reanalysis of these samples were to establish lower limits of determination for some elements and to confirm the NURE data as a reliable predictive reconnaissance tool for future studies in Alaska's Eagle 3? Quadrangle. This study has wide implications for using the archived NURE samples and data throughout Alaska for future studies.

  15. FY10 RARE Final Report to Region 10: The functional Assessment of Alaska Peatlands in Cook Inlet Basin - report

    EPA Science Inventory

    Peatlands in south central Alaska form the predominant wetland class in the lowlands that encompass Cook Inlet. These peatlands are also in areas of increasing human development in Alaska. Currently Alaska peatlands are extensive and largely pristine. This study focused onobtaini...

  16. Abundance, trends and distribution of baleen whales off Western Alaska and the central Aleutian Islands

    NASA Astrophysics Data System (ADS)

    Zerbini, Alexandre N.; Waite, Janice M.; Laake, Jeffrey L.; Wade, Paul R.

    2006-11-01

    Large whales were extensively hunted in coastal waters off Alaska, but current distribution, population sizes and trends are poorly known. Line transect surveys were conducted in coastal waters of the Aleutian Islands and the Alaska Peninsula in the summer of 2001-2003. Abundances of three species were estimated by conventional and multiple covariate distance sampling (MCDS) methods. Time series of abundance estimates were used to derive rates of increase for fin whales ( Balaenoptera physalus) and humpback whales ( Megaptera novaeangliae). Fin whales occurred primarily from the Kenai Peninsula to the Shumagin Islands, but were abundant only near the Semidi Islands and Kodiak. Humpback whales were found from the Kenai Peninsula to Umnak Island and were more abundant near Kodiak, the Shumagin Islands and north of Unimak Pass. Minke whales ( B. acutorostrata) occurred primarily in the Aleutian Islands, with a few sightings south of the Alaska Peninsula and near Kodiak Island. Humpback whales were observed in large numbers in their former whaling grounds. In contrast, high densities of fin whales were not observed around the eastern Aleutian Islands, where whaling occurred. Average abundance estimates (95% CI) for fin, humpback and minke whales were 1652 (1142-2389), 2644 (1899-3680), and 1233 (656-2315), respectively. Annual rates of increase were estimated at 4.8% (95% CI=4.1-5.4%) for fin and 6.6% (5.2-8.6%) for humpback whales. This study provides the first estimate of the rate of increase of fin whales in the North Pacific Ocean. The estimated trends are consistent with those of other recovering baleen whales. There were no sightings of blue or North Pacific right whales, indicating the continued depleted status of these species.

  17. Investigation of Genetic Variation Underlying Central Obesity amongst South Asians

    PubMed Central

    Scott, William R.; Zhang, Weihua; Loh, Marie; Tan, Sian-Tsung; Lehne, Benjamin; Afzal, Uzma; Peralta, Juan; Saxena, Richa; Ralhan, Sarju; Wander, Gurpreet S.; Bozaoglu, Kiymet; Sanghera, Dharambir K.; Elliott, Paul; Scott, James; Chambers, John C.; Kooner, Jaspal S.

    2016-01-01

    South Asians are 1/4 of the world’s population and have increased susceptibility to central obesity and related cardiometabolic disease. Knowledge of genetic variants affecting risk of central obesity is largely based on genome-wide association studies of common SNPs in Europeans. To evaluate the contribution of DNA sequence variation to the higher levels of central obesity (defined as waist hip ratio adjusted for body mass index, WHR) among South Asians compared to Europeans we carried out: i) a genome-wide association analysis of >6M genetic variants in 10,318 South Asians with focused analysis of population-specific SNPs; ii) an exome-wide association analysis of ~250K SNPs in protein-coding regions in 2,637 South Asians; iii) a comparison of risk allele frequencies and effect sizes of 48 known WHR SNPs in 12,240 South Asians compared to Europeans. In genome-wide analyses, we found no novel associations between common genetic variants and WHR in South Asians at P<5x10-8; variants showing equivocal association with WHR (P<1x10-5) did not replicate at P<0.05 in an independent cohort of South Asians (N = 1,922) or in published, predominantly European meta-analysis data. In the targeted analyses of 122,391 population-specific SNPs we also found no associations with WHR in South Asians at P<0.05 after multiple testing correction. Exome-wide analyses showed no new associations between genetic variants and WHR in South Asians, either individually at P<1.5x10-6 or grouped by gene locus at P<2.5x10−6. At known WHR loci, risk allele frequencies were not higher in South Asians compared to Europeans (P = 0.77), while effect sizes were unexpectedly smaller in South Asians than Europeans (P<5.0x10-8). Our findings argue against an important contribution for population-specific or cosmopolitan genetic variants underlying the increased risk of central obesity in South Asians compared to Europeans. PMID:27195708

  18. Rhyolitic calderas of the Yukon-Tanana Terrane, east central Alaska: volcanic remnants of a mid-Cretaceous magmatic arc

    USGS Publications Warehouse

    Bacon, C.R.; Foster, H.L.; Smith, James G.

    1990-01-01

    Four large but poorly exposed rhyolitic calderas are present in the Yukon-Tanana terrane (YTT) in east central Alaska. At least two are mid-Cretaceous in age (~93 Ma). Similar volcanic rocks, the South Fork Volcanics, occur northeast of the Tintina fault in Yukon Territory. Evidence for the calderas consists of thick deposits of devitrified crystal- and lithic-rich densely welded tuff, interpreted as caldera fill, associated with lava domes or shallow intrusive rocks. Coeval outflow sheets have been largely stripped by erosion. The calderas are preserved within a northeast trending depression extending across the axis of the elongate mid-Cretaceous plutonic province. Trace element abundances in andesites and rhyolites associated with the caldera structures are similar to those of volcanic and plutonic rocks of subduction-related magmatic arcs developed on continental crust and thus are suggestive of formation in such an environment. Late Cretaceous and early Tertiary igneous rocks in the YTT near the calderas are interpreted to have been emplaced in a more extensional setting when the subduction-related magmatic front was farther oceanward. -Authors

  19. ELECTRICAL LINES ARRIVE FROM CENTRAL FACILITIES AREA, SOUTH OF MTR. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    ELECTRICAL LINES ARRIVE FROM CENTRAL FACILITIES AREA, SOUTH OF MTR. EXCAVATION RUBBLE IN FOREGROUND. CONTRACTOR CRAFT SHOPS, CRANES, AND OTHER MATERIALS ON SITE. CAMERA FACES EAST, WITH LITTLE BUTTE AND MIDDLE BUTTE IN DISTANCE. INL NEGATIVE NO. 335. Unknown Photographer, 7/1/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

  20. 77 FR 48950 - South Central Idaho Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-15

    ...The South Central Idaho Resource Advisory Committee will meet in Jerome, Idaho. The committee is authorized under the Secure Rural Schools and Community Self-Determination Act (Pub. L. 112-141) (the Act) and operates in compliance with the Federal Advisory Committee Act. The purpose of the committee is to improve collaborative relationships and to provide advice and recommendations to the......

  1. 18. SOUTH CENTRAL SECTION OF HISTORIC DISTRICT LOOKING NORTH TO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. SOUTH CENTRAL SECTION OF HISTORIC DISTRICT LOOKING NORTH TO WATER TOWER (Buildings No. 43, 42, 78) (Copy negative made from National Archives negative No. 92-F-61B-5) - Fort Sheridan, 25 miles Northeast of Chicago, on Lake Michigan, Lake Forest, Lake County, IL

  2. This image, looking due south shows the central part of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    This image, looking due south shows the central part of the north wing of the building, a 2 story facade. In the foreground are several utility chases which span this elevation of the building - Department of Energy, Mound Facility, Electronics Laboratory Building (E Building), One Mound Road, Miamisburg, Montgomery County, OH

  3. 75 FR 8645 - South Central Idaho Resource Advisory Council

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-25

    ..., USDA. ACTION: Notice of meeting. SUMMARY: The South Central Idaho RAC will meet in Twin Falls, Idaho... meeting will be held at The Red Lion Canyon Springs Hotel, 1357 Blue Lakes Blvd. North, Twin Falls, Idaho... Road East, Twin Falls, Idaho 83301. Comments may also be sent via e-mail to jathomas@fs.fed.us , or...

  4. GENERAL VIEW FROM THE SOUTH, SHOWING CENTRAL COMPLEX WITH THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    GENERAL VIEW FROM THE SOUTH, SHOWING CENTRAL COMPLEX WITH THE STOCK BINS FOR RAW MATERIALS IN THE FOREGROUND, FOUR LARGE BOILER UNITS AND STOVE'S AND THE #1 BLAST FURNACE WITH SKIP HOIST IN THE BACKGROUND. - Sloss-Sheffield Steel & Iron, First Avenue North Viaduct at Thirty-second Street, Birmingham, Jefferson County, AL

  5. Introduction: seismology and earthquake engineering in Central and South America.

    USGS Publications Warehouse

    Espinosa, A.F.

    1983-01-01

    Reports the state-of-the-art in seismology and earthquake engineering that is being advanced in Central and South America. Provides basic information on seismological station locations in Latin America and some of the programmes in strong-motion seismology, as well as some of the organizations involved in these activities.-from Author

  6. 76 FR 14898 - South Central Idaho Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-18

    ...: Notice of meeting. SUMMARY: The South Central Idaho Resource Advisory Committee will meet in Sun Valley... meeting will be held March 30, 2011, 9:30 a.m. ADDRESSES: The meeting will be held at the Sun Valley City Hall Council Chambers, 810 Elkhorn Road, Sun Valley, Idaho 83353. Written comments should be sent...

  7. 50 CFR Figure 7 to Subpart E of... - Western and Central Alaska Rural and Non-Rural Areas

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Western and Central Alaska Rural and Non-Rural Areas 7 Figure 7 to Subpart E of Part 300 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS Pacific Halibut Fisheries Pt. 300, Subpt. E, Fig. 7 Figure...

  8. 50 CFR Figure 7 to Subpart E of... - Western and Central Alaska Rural and Non-Rural Areas

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 11 2013-10-01 2013-10-01 false Western and Central Alaska Rural and Non-Rural Areas 7 Figure 7 to Subpart E of Part 300 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS Pacific Halibut Fisheries Pt. 300, Subpt. E, Fig. 7 Figure...

  9. 50 CFR Figure 7 to Subpart E of... - Western and Central Alaska Rural and Non-Rural Areas

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Western and Central Alaska Rural and Non-Rural Areas 7 Figure 7 to Subpart E of Part 300 Wildlife and Fisheries INTERNATIONAL FISHING AND RELATED ACTIVITIES INTERNATIONAL FISHERIES REGULATIONS Pacific Halibut Fisheries Pt. 300, Subpt. E, Fig. 7 Figure 7 to Subpart E of Part 300—Western...

  10. 77 FR 75966 - Control Date for Qualifying Landings History in the Central Gulf of Alaska Trawl Groundfish...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-26

    ...; 63 FR 52642). Over the course of the past few years, the Council has recommended amendments to the... (77 FR 42629, July 20, 2012). In June 2012, the Council recommended an FMP amendment to reduce halibut... Landings History in the Central Gulf of Alaska Trawl Groundfish Fisheries AGENCY: National Marine...

  11. The south-central United States magnetic anomaly

    NASA Technical Reports Server (NTRS)

    Starich, P. J.; Hinze, W. J.; Braile, L. W.

    1985-01-01

    A positive magnetic anomaly, which dominates the MAGSAT scalar field over the south-central United States, results from the superposition of magnetic effects from several geologic sources and tectonic structures in the crust. The highly magnetic basement rocks of this region show good correlation with increased crustal thickness, above average crustal velocity and predominantly negative free-air gravity anomalies, all of which are useful constraints for modeling the magnetic sources. The positive anomaly is composed of two primary elements. The western-most segment is related to middle Proterozoic granite intrusions, rhyolite flows and interspersed metamorphic basement rocks in the Texas panhandle and eastern New Mexico. The anomaly and the magnetic crust are bounded to the west by the north-south striking Rio Grande Rift. The anomaly extends eastward over the Grenville age basement rocks of central Texas, and is terminated to the south and east by the buried extension of the Ouachita System. The northern segment of the anomaly extends eastward across Oklahoma and Arkansas to the Mississippi Embayment. It corresponds to a general positive magnetic region associated with the Wichita Mountains igneous complex in south-central Oklahoma and 1.2 to 1.5 Ga. felsic terrane to the north.

  12. Detrital Zircon Geochronology of Cretaceous and Paleogene Strata Across the South-Central Alaskan Convergent Margin

    USGS Publications Warehouse

    Bradley, Dwight; Haeussler, Peter; O'Sullivan, Paul; Friedman, Rich; Till, Alison; Bradley, Dan; Trop, Jeff

    2009-01-01

    Ages of detrital zircons are reported from ten samples of Lower Cretaceous to Paleogene metasandstones and sandstones from the Chugach Mountains, Talkeetna Mountains, and western Alaska Range of south-central Alaska. Zircon ages are also reported from three igneous clasts from two conglomerates. The results bear on the regional geology, stratigraphy, tectonics, and mineral resource potential of the southern Alaska convergent margin. Chugach Mountains - The first detrital zircon data are reported here from the two main components of the Chugach accretionary complex - the inboard McHugh Complex and the outboard Valdez Group. Detrital zircons from sandstone and two conglomerate clasts of diorite were dated from the McHugh Complex near Anchorage. This now stands as the youngest known part of the McHugh Complex, with an inferred Turonian (Late Cretaceous) depositional age no older than 91-93 Ma. The zircon population has probability density peaks at 93 and 104 Ma and a smattering of Early Cretaceous and Jurassic grains, with nothing older than 191 Ma. The two diorite clasts yielded Jurassic U-Pb zircon ages of 179 and 181 Ma. Together, these findings suggest a Mesozoic arc as primary zircon source, the closest and most likely candidate being the Wrangellia composite terrane. The detrital zircon sample from the Valdez Group contains zircons as young as 69 and 77 Ma, consistent with the previously assigned Maastrichtian to Campanian (Late Cretaceous) depositional age. The zircon population has peaks at 78, 91, 148, and 163 Ma, minor peaks at 129, 177, 330, and 352 Ma, and no concordant zircons older than Devonian. A granite clast from a Valdez Group conglomerate yielded a Triassic U-Pb zircon age of 221 Ma. Like the McHugh Complex, the Valdez Group appears to have been derived almost entirely from Mesozoic arc sources, but a few Precambrian zircons are also present. Talkeetna Mountains - Detrital zircons ages were obtained from southernmost metasedimentary rocks of the

  13. Central Energy System Modernization at Fort Jackson, South Carolina

    SciTech Connect

    Brown, Daryl R.; Chvala, William D.; Dirks, James A.

    2006-11-29

    An evaluation of technology options was conducted for the central energy systems at Fort Jackson, South Carolina. There were two objectives in conducting this study. From a broader viewpoint, the Army would like to develop a systematic approach to management of its central energy systems and selected Fort Jackson for this ''pilot'' study for a prospective Central Energy System Modernization Program. From a site-specific perspective, the objective was to identify the lowest life-cycle cost energy supply option(s) at Fort Jackson for buildings currently served by central boilers and chillers. This study was co-funded by the Army's Southeast Region and the U.S. Department of Energy's Federal Energy Management Program.

  14. Trends of ice breakup date in south-central Ontario

    NASA Astrophysics Data System (ADS)

    Fu, Congsheng; Yao, Huaxia

    2015-09-01

    Large-scale ice phenology studies have revealed overall patterns of later freeze, earlier breakup, and shorter duration of ice in the Northern Hemisphere. However, there have been few studies regarding the trends, including their spatial patterns, in ice phenology for individual waterbodies on a local or small regional scale, although the coherence of ice phenology has been shown to decline rapidly in the first few hundred kilometers. In this study, we extracted trends, analyzed affecting factors, and investigated relevant spatial patterns for ice breakup date time series at 10 locations with record length ≥90 years in south-central Ontario, Canada. Wavelet methods, including the multiresolution analysis (MRA) method for nonlinear trend extraction and the wavelet coherence (WTC) method for identifying the teleconnections between large-scale climate modes and ice breakup date, are proved to be effective in ice phenology analysis. Using MRA method, the overall trend of ice breakup date time series (1905-1991) varied from earlier ice breakup to later ice breakup, then to earlier breakup again from south to north in south-central Ontario. Ice breakup date is closely correlated with air temperature during certain winter/spring months, as well as the last day with snow on the ground and number of snow-on-ground days. The influences of solar activity and Pacific North American on ice breakup were comparatively uniform across south-central Ontario, while those of El Niño-Southern Oscillation, North Atlantic Oscillation, and Arctic Oscillation on ice phenology changed with distance of 50-100 km in the north-south direction.

  15. South America, Central America, the Caribbean, and Mexico

    SciTech Connect

    Deal, C.

    1981-10-01

    Summaries of oil and gas drillings, well completions, production, exploratory wells, exploration activity and wildcat drilling were given for South America, Central America, the Caribbean, and Mexico. The countries, islands, etc. included Argentina, Bahamas, Barbados, Belize, Bolivia, Brazil, Colombia, Costa Rica, Cuba, Dominican Republic, Ecuador, French Guiana, Guatemala, Guyana, Haiti, Honduras, Jamaica, Leeward and Windward Islands, Mexico, Netherlands Antilles, Nicaragua, Panama, Paraguay, Peru, Puerto Rico, El Salvador, Surinam, Trinidad and Venezuela. 16 figures, 120 tables. (DP)

  16. Hydrology of the Arbuckle Mountains area, south-central Oklahoma

    USGS Publications Warehouse

    Fairchild, Roy W.; Hanson, Ronald L.; Davis, Robert E.

    1990-01-01

    Rocks that make up the Arbuckle-Simpson aquifer crop out over ~500 mi2 in the Arbuckle Mountains province in south-central Oklahoma. The aquifer consists of limestone, dolomite, and sandstone of the Arbuckle and Simpson Groups of Late Cambrian to Middle Ordovician age and is about 5,000-9,000 ft thick. The rocks were subjected to intensive folding and faulting associated with major uplift of the area during Early to Late Pennsylvanian time.

  17. Observations of TEC Depletions in South and Central America

    NASA Astrophysics Data System (ADS)

    Valladares, C. E.; Sheehan, R. E.; Pradipta, R.

    2014-12-01

    TEC values gathered with several networks of GPS receivers, which operated in South and Central America and the Caribbean region between 2010 and 2013, have been used to investigate the characteristics and morphology of TEC depletions that develop at these locations. In South America the TEC depletions are associated with low-latitude plasma bubbles. In Central America and the Caribbean region, we found that TEC depletions that occur during magnetically active conditions (Kp > 5o), persist for very long periods and sometimes remain even during afternoon hours. During quiet magnetic conditions, TEC depletions occur around the June solstice in Central America and during the December solstice in the Southern part of South America. We have also studied possible links between mid-latitude depletions and the formation of plasma bubbles at low latitudes. In addition, TEC measurements from North America have been utilized to determine the poleward extension of the mid-latitude depletions. These depletions do not appear to be related to auroral plasma processes or to storm enhanced densities (SED). We are studying the possibility that their initiation process is associated with the disturbance dynamo or the prompt penetrating electric field that develop during storm conditions.

  18. 40 CFR 81.166 - South Central Coast Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 17 2011-07-01 2011-07-01 false South Central Coast Intrastate Air... Air Quality Control Regions § 81.166 South Central Coast Intrastate Air Quality Control Region. The South Central Coast Intrastate Air Quality Control Region (California) consists of the territorial...

  19. Distribution of burrowing owls in east-central South Dakota

    USGS Publications Warehouse

    Shaffer, Jill A; Thiele, Jason P.

    2013-01-01

    Western burrowing owl (Athene cunicularia hypugaea) populations have declined across much of western North America, particularly at the northern and eastern edges of the species’ breeding range (Martell et al. 2001, Murphy et al. 2001, Shyry et al. 2001, Skeel et al. 2001, Klute et al. 2003). In South Dakota, the burrowing owl is a summer resident that historically was relatively common throughout the state, but its range has decreased in recent decades, especially in the eastern half of the state (Whitney et al. 1978, South Dakota Ornithologists’ Union [SDOU] 1991, Peterson 1995). Tallman et al. (2002) described the species as uncommon to locally common in western South Dakota, uncommon in the north-central part of the state, and casual (i.e., not within the species’ normal range, but with 3–10 records in the past 10 years) elsewhere in the eastern half. The burrowing owl is a Species of Greatest Conservation Need (South Dakota Department of Game, Fish and Parks [SDGFP] 2006) and a Level I Priority Species in South Dakota (Bakker 2005).

  20. Stratiform zinc-lead mineralization in Nasina assemblage rocks of the Yukon-Tanana Upland in east-central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, Cynthia; Bressler, Jason R.; Takaoka, Hidetoshi; Mortensen, James K.; Oliver, Douglas H.; Leventhal, Joel S.; Newberry, Rainer J.; Bundtzen, Thomas K.

    1998-01-01

    The Yukon-Tanana Upland of east-central Alaska and Yukon comprises thrust sheets of ductilely deformed metasedimentary and metaigneous rocks of uncertain age and origin that are overlain by klippen of weakly metamorphosed oceanic rocks of the Seventymile-Slide Mountain terrane, and intruded by post-kinematic Early Jurassic, Cretaceous and Tertiary granitoids. Metamorphosed continental margin strata in the Yukon-Tanana Upland of east-central Alaska are thought to be correlative, on the basis of stratigraphic similarities and sparse Mississippian U-Pb zircon and fossil ages (Mortensen, 1992), with middle Paleozoic metasedimentary and metavolcanic rocks in the eastern Alaska Range and in western and southeastern Yukon. Furthermore, rocks in the northern Yukon-Tanana Upland may correlate across the Tintina fault with unmetamorphosed counterparts in the Selwyn Basin (Murphy and Abbott, 1995). Volcanic-hosted (VMS) and sedimentary exhalative (sedex) massive sulfide occurrences are widely reported for these other areas (green-colored unit of fig. 1) but, as yet, have not been documented in the Alaskan part of the Yukon-Tanana Upland. Recent discoveries of VMS deposits in Devono-Mississippian metavolcanic rocks in the Finlayson Lake area of southeastern Yukon (Hunt, 1997) have increased the potential for finding VMS deposits in rocks of similar lithology and age in the Yukon-Tanana Upland of Alaska. Restoration of 450 km of early Tertiary dextral movement along the Tintina fault juxtaposes these two areas.

  1. Combined Ice and Water Balances of Maclure Glacier, California, South Cascade Glacier, Washington, and Wolverine and Gulkana Glaciers, Alaska, 1967 Hydrologic Year

    USGS Publications Warehouse

    Tangborn, Wendell V.; Mayo, Lawrence R.; Scully, David R.; Krimmel, Robert M.

    1977-01-01

    Combined ice and water balances were measured in the 1967 hydrologic year (October 1-September 30) on four glaciers in western North America ranging in latitude from 37 deg to 63 deg N. This hydrologic year was characterized by heavier than normal winter precipitation in California and Washington and abnormally dry winter conditions in coastal Alaska. In summer the western conterminous states were abnormally dry and central and southern Alaska experienced very wet conditions. Maclure Glacier (lat 37 deg 45' N., 3,650-m (metres) mean equilibrium line altitude) had an above normal winter balance of 3.46 m and a positive annual balance of 1.05 m (metres of water equivalent). South Cascade Glacier (lat 48 deg 22' N., 1900-m mean equilibrium line altitude) had a winter balance of 3.28 m, slightly above average. Above normal summer ablation resulted in a final annual balance of -0.58 m, slightly more negative than has been the case for the past decade. Wolverine Glacier's (lat 60 deg 24' N., 1,200-m mean equilibrium line altitude) winter balance was 1.17 m, considerably below normal; the annual balance was -2.04 m. Gulkana Glacier (lat 63 deg 15' N., 1,700-m mean equilibrium line altitude) had a winter balance of 1.05 m, approximately normal for this glacier; the final annual balance was -0.30 m.

  2. Evidence for formation of a flexural backarc basin by compression and crustal thickening in the central Alaska peninsula

    SciTech Connect

    Bond, G.C.; Lewis, S.D.; Taber, J.; Steckler, M.S.; Kominz, M.A. )

    1988-12-01

    The North Aleutian Basin is a large, Cenozoic sedimentary basin in the northern part of the central Alaska Peninsula and the southern Bering shelf. The gravity anomaly pattern, the geometry, and the structure of the basin suggest that if formed by downward flexure of the backarc lithosphere. Basin modeling suggests that the flexure was driven by the emplacement of surface and subsurface loads having densities comparable to those of oceanic crust and mantle rocks, at approximately the position of the present-day volcanic arc and forearc. The authors suggest that the inferred loads consist of tectonically thickened mafic crustal materials lying beneath the arc and forearc of the central Alaska Peninsula. The crustal thickening may have occurred within a dominantly transpressional regime resulting from oblique convergence between the North American and Pacific plates during the Cenozoic.

  3. Central and South America GPS geodesy - CASA Uno

    NASA Technical Reports Server (NTRS)

    Kellogg, James N.; Dixon, Timothy H.

    1990-01-01

    In January 1988, scientists from over 25 organizations in 13 countries and territories cooperated in the largest GPS campaign in the world to date. A total of 43 GPS receivers collected approximately 590 station-days of data in American Samoa, Australia, Canada, Colombia, Costa Rica, Ecuador, New Zealand, Norway, Panama, Sweden, United States, West Germany, and Venezuela. The experiment was entitled CASA Uno. Scientific goals of the project include measurements of strain in the northern Andes, subduction rates for the Cocos and Nazca plates beneath Central and South America, and relative motion between the Caribbean plate and South America. A second set of measurements are planned in 1991 and should provide preliminary estimates of crustal deformation and plate motion rates in the region.

  4. Denali fault slip rates and Holocene-late Pleistocene kinematics of central Alaska

    USGS Publications Warehouse

    Matmon, A.; Schwartz, D.P.; Haeussler, P.J.; Finkel, R.; Lienkaemper, J.J.; Stenner, H.D.; Dawson, T.E.

    2006-01-01

    The Denali fault is the principal intracontinental strike-slip fault accommodating deformation of interior Alaska associated with the Yakutat plate convergence. We obtained the first quantitative late Pleistocene-Holocene slip rates on the Denali fault system from dating offset geomorphic features. Analysis of cosmogenic 10Be concentrations in boulders (n = 27) and sediment (n = 13) collected at seven sites, offset 25-170 m by the Denali and Totschunda faults, gives average ages that range from 2.4 ± 0.3 ka to 17.0 ± 1.8 ka. These offsets and ages yield late Pleistocene-Holocene average slip rates of 9.4 ± 1.6, 12.1 ± 1.7, and 8.4 ± 2.2 mm/yr-1 along the western, central, and eastern Denali fault, respectively, and 6.0 ± 1.2 mm/yr-1 along the Totschunda fault. Our results suggest a westward decrease in the mean Pleistocene-Holocene slip rate. This westward decrease likely results from partitioning of slip from the Denali fault system to thrust faults to the north and west. 2006 Geological Society of America.

  5. Early Miocene mylonitization and detachment faulting, South Mountains, central Arizona

    SciTech Connect

    Reynolds, S.J.; Shafiqullah, M.; Damon, P.E.; DeWitt, E.

    1986-04-01

    The South Mountains of central Arizona are one of the geologically simplest metamorphic core complexes of the North American Cordillera. An early Miocene age of mylonitization is indicated by crosscutting relationships between mylonitic fabric and a composite pluton dated at 22-25 Ma by Rb-Sr, U-Th-Pb, and K-Ar techniques. The kinematic agreement and close temporal association of mylonitization and detachment faulting support models in which the two processes are related to an evolving crustal shear zone that accommodated mid-Tertiary continental extension. 19 references, 3 figures, 2 tables.

  6. Facies comparison of autochthonous and allochthonous Permian and Triassic units, north-central Brooks Range, Alaska

    SciTech Connect

    Adams, K.E.

    1985-04-01

    Eight stratigraphic sections of Permian and Triassic rocks have been studied over a 30 km by 150 km area in the Endicott and Philip Smith Mountains of the central Brooks Range. Six of the sections are located on the Endicott Mountains allochthon, and the remaining two are parautochthonous columns in the Mount Doonerak area. The sections record a facies transition between the autochthonous Sadlerochit Group and Shublik Formation of the northeastern Brooks Range and the characteristically siliceous rocks of the allochthonous Siksikpuk and Otuk formations of the western Brooks Range. Laterally continuous and bioturbated beds of fine-grained sandstone, siltstone, and shale dominantly compose the Permian sequence, whereas the Triassic rocks consist of black shales, thin rhythmically bedded siliceous mudstones, and fossiliferous limestones. When the allochthonous sections are restored to a position south of the Mount Doonerak area, a general shallowing trend from southwest to northwest becomes evident within the reconstructed marine basin. To the south and west, the Permian sediments show a marked increase in silica content, with the occurrence of barite and a corresponding decrease in the thickness of the basal, coarser grained clastics. The Triassic formations also document an increase in silica and the presence of barite to the south and west, while becoming significantly sooty and phosphatic to the north and east. Ongoing petrographic and micropaleontologic studies of the field data will clarify these general paleogeographic relationships.

  7. Geologic Map and Engineering Properties of the Surficial Deposits of the Tok Area, East-Central Alaska

    USGS Publications Warehouse

    Carrara, Paul E.

    2007-01-01

    The Tok area 1:100,000-scale map, through which the Alaska Highway runs, is in east-central Alaska about 160 km west of the Yukon border. The surficial geologic mapping in the map area is in support of the 'Geologic Mapping in support of land, resources, and hazards issues in Alaska' Project of the USGS National Cooperative Geologic Mapping Program. The Tok map area contains parts of three physiographic provinces, the Alaska Range, the Yukon-Tanana Upland, and the Northway-Tanana Lowland. The high, rugged, glaciated landscape of the eastern Alaska Range dominates the southwestern map area. The highest peak, an unnamed summit at the head of Cathedral Rapids Creek No. 2, rises to 2166 m. The gently rolling hills of the Yukon-Tanana Upland, in the northern map area, rise to about 1000 m. The Northway-Tanana Lowland contains the valley of the westerly flowing Tanana River. Elevations along the floor of the lowland generally range between 470 and 520 m. The dominant feature within the map is the Tok fan, which occupies about 20 percent of the map area. This large (450 km2), nearly featureless fan contains a high percentage of volcanic clasts derived from outside the present-day drainage of the Tok River. Because the map area is dominated by various surficial deposits, the map depicts 26 different surficial units consisting of man-made, alluvial, colluvial, eolian, lacustrine, organic, glaciofluvial, glacial, and periglacial deposits. The accompanying table provides information concerning the various units including their properties, characteristics, resource potential, and associated hazards in this area of the upper Tanana valley.

  8. Petroleum source potential and thermal maturity of Cantwell Formation (Paleocene), central Alaska Range: a reconnaissance study

    SciTech Connect

    Stanley, R.G.

    1987-05-01

    The Paleocene Cantwell Formation is a sequence of nonmarine sedimentary and volcanic rocks that is widely distributed in the central Alaska Range and locally is more than 3000 m thick. Mudstones and coals in the Cantwell were deposited in a variety of lacustrine and fluvial overbank environments and are of interest as potential source rocks of petroleum. Thirty-eight samples of mudstone and coal were collected from ten outcrops and analyzed using Rock-Eval pyrolysis, vitrinite reflectance (R/sub 0/), and thermal alteration index (TAI). The results suggest that these rocks may be potential sources of gas and possibly oil. Total organic carbon (TOC) in the samples is relatively high, averaging about 2.8% (range 0.5-14.2%) in the mudstones and about 28.8% (range 5.1-50.2%) in the coals. Plots of hydrogen and oxygen indices (HI and OI) on modified van Krevelen diagrams indicate kerogens of types III and IV. In addition, HI values are generally less than 150 and S2/S3 values are generally less than 3, indicating that these kerogens are gas prone. A few samples exhibit somewhat higher values of HI (up to 170) and S2/S3 (up to 18.6) and therefore may be capable of generating small amounts of oil. Values of T/sub max/ (range 437-537/sup 0/C), median R/sub 0/ (range 0.63-4.28), and TAI (range 2.3.-3.8) show that the thermal maturity of the samples varies from mature to postmature with respect to the oil and gas windows.

  9. New glass sponges (Porifera: Hexactinellida) from deep waters of the central Aleutian Islands, Alaska.

    PubMed

    Reiswig, Henry M; Stone, Robert P

    2013-01-01

    Hexactinellida from deep-water communities of the central Aleutian Islands, Alaska, are described. They were mostly collected by the remotely operated vehicle 'Jason II' from 494–2311 m depths during a 2004 RV 'Roger Revelle' expedition, but one shallow-water species collected with a shrimp trawl from 155 m in the same area is included. The excellent condition of the ROV-collected specimens enabled valuable redescription of some species previously known only from badly damaged specimens. New taxa include one new genus and eight new species in five families. Farreidae consist of two new species, Farrea aleutiana and F. aspondyla. Euretidae consists of only Pinulasma fistulosum n. gen., n. sp. Tretodictyidae include only Tretodictyum amchitkensis n. sp. Euplectellidae consists of only the widespread species Regadrella okinoseana Ijima, reported here over 3,700 km from its closest previously known occurrence. The most diverse family, Rossellidae, consists of Aulosaccus ijimai (Schulze), Aulosaccus schulzei Ijima, Bathydorus sp. (young stage not determinable to species), Caulophacus (Caulophacus) adakensis n. sp., Acanthascus koltuni n. sp., Staurocalyptus psilosus n. sp., Staurocalyptus tylotus n. sp. and Rhabdocalyptus mirabilis Schulze. We present argument for reinstatement of the abolished rossellid subfamily Acanthascinae and return of the subgenera  Staurocalyptus Ijima and Rhabdocalyptus Schulze to their previous generic status. These fauna provides important complexity to the hard substrate communities that likely serve as nursery areas for the young stages of commercially important fish and crab species, refuge from predation for both young and adult stages, and also as a focal source of prey for juvenile and adult stages of those same species. PMID:25325089

  10. Geologic and isostatic map of the Nenana Basin area, central Alaska

    USGS Publications Warehouse

    Frost, G.M.; Barnes, D.F.; Stanley, R.G.

    2002-01-01

    Introduction The Nenana Basin area is a prospective petroleum province in central Alaska, and this geologic and isostatic gravity map is part of a petroleum resource assessment of the area. The geology was compiled from published sources (Chapman and others, 1971, 1975a, 1975b, 1982; Chapman and Yeend, 1981; Csejtey and others, 1986; Jones and others, 1983; Pewe and others, 1966; Reed, 1961; and Weber and others, 1992), as shown on the index map (map sheet). Map units are organized and presented according to the scheme of lithotectonic terranes proposed by Jones and others (1987) and Silberling and Jones (1984); we recognize, however, that this terrane scheme is controversial and likely to be revised in the future. In some cases, we combined certain terranes because we were unable to match the terrane boundaries given by Jones and others (1987) and Silberling and Jones (1984) with specific faults shown on existing geologic maps. Postaccretion cover deposits represent overlap assemblages that depositionally overlie accreted terranes. Plutonic igneous rocks shown on this map include several plutons that are clearly postaccretionary, based on isotopic ages and (or) field relations. It is possible that some of the plutons predate accretion, but this has not been demonstrated. According to Jones and others (1982), the terranes in the area of our map were assembled during late Mesozoic or earliest Cenozoic time. The gravity contours are derived from data used in earlier compilations (Barnes, 1961, 1977; Hackett, 1981; Valin and others, 1991; Frost and Stanley, 1991) that are supplemented by some National Oceanic and Atmospheric Administration data along the Alaska Pipeline level line (W.E. Strange, written commun., 1980). The earlier compilations were used for simple Bouguer maps, prepared primarily by non-digital methods, and are superseded by this map. The present map is the result of digital processing that includes the 1967 Geodetic Reference System, the IGSN-71

  11. Alaska Glaciers and Rivers

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image on October 7, 2007, showing the Alaska Mountains of south-central Alaska already coated with snow. Purple shadows hang in the lee of the peaks, giving the snow-clad land a crumpled appearance. White gives way to brown on the right side of the image where the mountains yield to the lower-elevation Susitna River Valley. The river itself cuts a silver, winding path through deep green forests and brown wetlands and tundra. Extending from the river valley, are smaller rivers that originated in the Alaska Mountains. The source of these rivers is evident in the image. Smooth white tongues of ice extend into the river valleys, the remnants of the glaciers that carved the valleys into the land. Most of the water flowing into the Gulf of Alaska from the Susitna River comes from these mountain glaciers. Glacier melt also feeds glacier lakes, only one of which is large enough to be visible in this image. Immediately left of the Kahiltna River, the aquamarine waters of Chelatna Lake stand out starkly against the brown and white landscape.

  12. Global GIS database; digital atlas of Central and South America

    USGS Publications Warehouse

    Hearn,, Paul P., Jr.; Hare, T.; Schruben, P.; Sherrill, D.; LaMar, C.; Tsushima, P.

    2000-01-01

    This CD-ROM contains a digital atlas of the countries of Central and South America. This atlas is part of a global database compiled from USGS and other data sources at the nominal scale of 1:1 million and is intended to be used as a regional-scale reference and analytical tool by government officials, researchers, the private sector, and the general public. The atlas includes free GIS software or may also be used with ESRI's ArcView software. Customized ArcView tools, specifically designed to make the atlas easier to use, are also included. The atlas contains the following datasets: country political boundaries, digital shaded relief map, elevation, slope, hydrology, locations of cities and towns, airfields, roads, railroads, utility lines, population density, geology, ecological regions, historical seismicity, volcanoes, ore deposits, oil and gas fields, climate data, landcover, vegetation index, and lights at night.

  13. Natural phenomena hazards, Hanford Site, south central Washington

    SciTech Connect

    Tallman, A.M.

    1996-04-16

    This document presents the natural phenomena hazard (NPH) loads for use in implementing DOE Order 5480.28, Natural Phenomena Hazards Mitigation, at the Hanford Site in south-central Washington State. The purpose of this document is twofold: (1) summarize the NPH that are important to the design and evaluation of structures, systems, and components at the Hanford Site; (2) develop the appropriate natural phenomena loads for use in the implementation of DOE Order 5480.28. The supporting standards, DOE-STD-1020-94, Natural Phenomena Hazards Design and Evaluation Criteria for Department of Energy Facilities (DOE 1994a); DOE-STD-1022-94, Natural Phenomena Hazards Site Characteristics Criteria (DOE 1994b); and DOE-STD-1023-95, Natural Phenomena Hazards Assessment Criteria (DOE 1995) are the basis for developing the NPH loads.

  14. Wind energy resource atlas. Volume 7. The south central region

    SciTech Connect

    Edwards, R.L.; Graves, L.F.; Sprankle, A.C.; Elliott, D.L.; Barchet, W.R.; George, R.L.

    1981-03-01

    This atlas of the south central region combines seven collections of wind resource data: one for the region, and one for each of the six states (Arkansas, Kansas, Louisiana, Missouri, Oklahoma, and Texas). At the state level, features of the climate, topography, and wind resource are discussed in greater detail than that provided in the regional discussion, and the data locations on which the assessment is based are mapped. Variations, over several time scales, in the wind resource at selected stations in each state are shown on graphs of monthly average and interannual wind speed and power, and hourly average wind speed for each season. Other graphs present speed, direction, and duration frequencies of the wind at these locations.

  15. The south-central United States magnetic anomaly

    NASA Technical Reports Server (NTRS)

    Hinze, W. J.; Braile, L. W. (Principal Investigator); Starich, P. J.

    1984-01-01

    The South-Central United States Magnetic Anomaly is the most prominent positive feature in the MAGSAT scalar magnetic field over North America. The anomaly correlates with increased crustal thickness, above average crustal velocity, negative free air gravity anomalies and an extensive zone of Middle Proterozoic anorogenic felsic basement rocks. Spherical dipole source inversion of the MAGSAT scalar data and subsequent calculation of reduced to pole and derivative maps provide constraints for a crustal magnetic model which corresponds geographically to the extensive Middle Proterozoic felsic rocks trending northeasterly across the United States. These felsic rocks contain insufficient magnetization or volume to produce the anomaly, but are rather indicative of a crustal zone which was disturbed during a Middle Proterozoic thermal event which enriched magnetic material deep in the crust.

  16. The south-central United States magnetic anomaly

    NASA Technical Reports Server (NTRS)

    Starich, P. J.

    1985-01-01

    The South-Central United States Magnetic Anomaly is the most prominent positive feature in the MAGSAT scalar magnetic field over North America. The anomaly correlates with increased crustal thickness, above average crustal velocity, negative free-air gravity anomalies and an extensive zone of Middle Proterozoic anorogenic felsic basement rocks. Spherical dipole source inversion of the MAGSAT scalar data and subsequent calculation of reduced-to-pole and derivative maps provide additional constraints for a crustal magnetic model which corresponds geographically to the extensive Middle Proterozoic felsic rocks trending northeasterly across the United States. These felsic rocks contain insufficient magnetization or volume to produce the anomaly, but are rather indicative of a crustal zone which was disturbed during a Middle Proterozoic thermal event which enriched magnetic material deep in the crust.

  17. The 2008 Eruption of Kasatochi Volcano, Central Aleutian Islands, Alaska: Reconnaissance Observations and Preliminary Physical Volcanology

    NASA Astrophysics Data System (ADS)

    Waythomas, C. F.; Schneider, D. J.; Prejean, S. G.

    2008-12-01

    The August 7, 2008 eruption of Kasatochi volcano was the first documented historical eruption of this small (3 x 3 km) island volcano with a 1 km2 lake filled crater in the central Aleutian Islands of Alaska. Reports of previous Kasatochi eruptions are unconfirmed and lacking in detail and little is known about the eruptive history. Three explosively-generated ash plumes reaching altitudes of 15 to 20 km were observed in satellite data and were preceded by some of the most intense seismicity yet recorded by the Alaska Volcano Observatory (AVO) seismic network. Eruptive products on Kasatochi Island observed on August 22 and 23 consist of pumice-bearing, lithic-rich pyroclastic-flow deposits overlain by a 1-2 m thick sequence of fine- grained pyroclastic-surge, and -fall deposits all exposed at the coastline. These deposits completely blanket Kasatochi Island to a depth of many meters. Pyroclastic flows entered the sea and extended the coastline 300-400 m beyond prominent wave cut cliffs and sea stacks. Tide gauge data from Adak Island, 80 km to the west, indicate a small tsunami with maximum water amplitude of 20 cm, was initiated during the eruption. Kasatochi volcano lacks a real-time seismic monitoring network. Seismic activity was detected by AVO instruments on Great Sitkin Island 40 km to the west, and thus the timing of eruptive events is approximate. The eruption began explosively at 2201 UTC on August 7, and was followed by at least two additional strong eruptive bursts at 0150 UTC and 0435 UTC, August 8. Satellite data show a significant ash cloud associated with the 0435 UTC event followed by at least 14 hours of continuous ash emission. The lack of a strong ash signature in satellite data suggest that the first two plumes were ash poor. Satellite data also show a large emission of SO2 that entered the stratosphere. Correlation of eruptive periods with deposits on the island is not yet possible, but it appears that pyroclastic flows were emplaced during

  18. Biogeochemical characterization of an undisturbed highly acidic, metal-rich bryophyte habitat, east-central Alaska, U.S.A.

    USGS Publications Warehouse

    Gough, L.P.; Eppinger, R.G.; Briggs, P.H.; Giles, S.

    2006-01-01

    We report on the geochemistry of soil and bryophyte-laden sediment and on the biogeochemistry of willows growing in an undisturbed volcanogenic massive sulfide deposit in the Alaska Range ecoregion of east-central Alaska. We also describe an unusual bryophyte assemblage found growing in the acidic metal-rich waters that drain the area. Ferricrete-cemented silty alluvial sediments within seeps and streams are covered with the liverwort Gymnocolea inflata whereas the mosses Polytrichum commune and P. juniperinum inhabit the area adjacent to the water and within the splash zone. Both the liverwort-encrusted sediment and Polytrichum thalli have high concentrations of major and trace metal cations (e.g., Al, As, Cu, Fe, Hg, La, Mn, Pb, and Zn). Soils in the area do not reflect the geochemical signature of the mineral deposit and we postulate they are influenced by the chemistry of eolian sediments derived from outside the deposit area. The willow, Salix pulchra, growing mostly within and adjacent to the larger streams, has much higher concentrations of Al, As, Cd, Cr, Fe, La, Pb, and Zn when compared to the same species collected in non-mineralized areas of Alaska. The Cd levels are especially high and are shown to exceed, by an order of magnitude, levels demonstrated to be toxic to ptarmigan in Colorado. Willow, growing in this naturally occurring metal-rich Red Mountain alteration zone, may adversely affect the health of browsing animals. ?? 2006 Regents of the University of Colorado.

  19. Airborne electromagnetic and magnetic geophysical survey data of the Yukon Flats and Fort Wainwright areas, central Alaska, June 2010

    USGS Publications Warehouse

    Ball, Lyndsay B.; Smith, Bruce D.; Minsley, Burke J.; Abraham, Jared D.; Voss, Clifford I.; Astley, Beth N.; Deszcz-Pan, Maria; Cannia, James C.

    2011-01-01

    In June 2010, the U.S. Geological Survey conducted airborne electromagnetic and magnetic surveys of the Yukon Flats and Fort Wainwright study areas in central Alaska. These data were collected to estimate the three-dimensional distribution of permafrost at the time of the survey. These data were also collected to evaluate the effectiveness of these geophysical methods at mapping permafrost geometry and to better define the physical properties of the subsurface in discontinuous permafrost areas. This report releases digital data associated with these surveys. Inverted resistivity depth sections are also provided in this data release, and data processing and inversion methods are discussed.

  20. The crustal structure of south central Mongolia using receiver functions

    NASA Astrophysics Data System (ADS)

    He, Jing; Wu, Qingju; Sandvol, Eric; Ni, James; Gallegos, Andrea; Gao, Mengtan; Ulziibat, Munkhuu; Demberel, Sodnomsambuu

    2016-06-01

    The crustal thickness H and average crustal velocity ratio k (Vp/Vs) beneath south central Mongolia are investigated using the H-k stacking method based on teleseismic radial receiver functions. Our primary results reveal that the local crustal thickness varies from 38 to 46 km with an average value of 43 km. Thicker crust is found beneath the western Hentey Mountains, while thinner crust is located in the southern area of the Zuunbayan fault zone. The Bouguer gravity anomalies exhibit a strong correlation with the overall crustal thickness pattern throughout most of our study regime. Moreover, a new approach which integrates the Bouguer anomaly gradient and the receiver function-derived crustal thickness is adopted to calculate the density of the lower crust underneath central Mongolia. Fairly dense lower crust of approximately 3000 kg/m3 is found in the Middle Gobi Desert. The measured crustal Vp/Vs ratio ranges from 1.68 to 1.83 with an average value of 1.74. Low Vp/Vs ratio is found beneath the western Hentey Mountains. In general, low Vp/Vs ratios correlate well with regions of quartz-rich crust and high heat flow. High Vp/Vs ratios occur in the Middle Gobi volcanic regions and the Mesozoic Southern Gobi Basin.

  1. The diorite at West Warren, south-central Massachusetts

    USGS Publications Warehouse

    Pomeroy, John S.

    1974-01-01

    Follated, syntectonic, concordant intrusive bodies of mostly diorite and meladiorite with less abundant quartz diorite and norite have been mapped in the West Warren area of south-central Massachusetts. The rocks of the pluton range from a medium colored phase of diorite and quartz diorite to a dark colored phase of meladiorite and norite. Major minerals In the dioritic rocks are calcic andesine, green hornblende, brown biotite, and hypersthene. Igneous textures are dominant, and retrograde or deuteric effects are generally minor. Silica and alumina contents of the dioritic rocks are somewhat higher than for average diorites; conversely, the oxides of iron, magnesium, and calcium are generally lower. Normative quartz, albite, and anorthite are higher and orthoclase is lower in the samples than In the average diorite. Sizeable plutons of diorite-norite are uncommon in central Massachusetts. The West Warren body, roughly 26 km2 (10 square miles) in area, bears little petrochemical relation to adjacent rock units. The pluton can be construed as belonging to a belt of intrusive mafic rocks which stretches from southeastern New York to coastal Maine.

  2. Basement involvement in the south-central Taiwan thrust belt

    NASA Astrophysics Data System (ADS)

    Brown, Dennis; Camanni, Giovanni; Alvarez, Joaquina; Ayala, Concepcion; Wu, Yih-Min; Hsieh, Hsien-Hsiang

    2015-04-01

    The Taiwan mountain belt is generally thought to develop above a shallow, through-going basal detachment confined to within the sedimentary cover of the Eurasian continental margin. Recently acquired surface geology, when combined with seismic tomography, earthquake hypocenter, and gravity data suggest, however, that basement is also involved in the deformation in south-central Taiwan. Since basement does not crop out in south central Taiwan, we adopt a P-wave velocity of 5.2 km/s has a proxy for the basement-cover interface and use it as a reference horizon. This interpretation is then tested as a density contrast by 3D modeling of the Bouguer anomaly data. The good fit between the two suggests that this surface provides a reasonable proxy as an interpretation for the top of the basement in what follows. The data suggests that, in the west, beneath the Coastal Plain and the Western Foothills, the mountain belt is evolving above a southward deepening level of detachment that is illuminated by sub-horizontal clusters of earthquake hypocenters located near the basement-cover interface. In much of the study area, this detachment appears to be below the depth of the basal thrust determined from geological constraints provided by the thrust system mapped at the surface. Furthermore, when viewed in a northwest-southeast orientation, the hypocenters cluster that defines the detachment appears to mimic the rugose extensional fault architecture imaged in the off shore to the west of Taiwan. This suggests that pre-existing faults on the margin, although oriented at a high angle to the convergence direction, are playing an active role in the development of thrust belt while still not being completely inverted. Eastward, the detachment at the basement-cover interface joins with an east-dipping hypocenter cluster that is interpreted to form a ramp that extends to greater than 20 km depth, into the middle crust. Above this ramp, basement rocks (P-wave > 5.2 km/s) are uplifted to

  3. The Middle Fork Plutonic Complex: A plutonic association of coeval peralkaline and metaluminous magmas in the north-central Alaska Range

    SciTech Connect

    Solie, D.N.

    1988-01-01

    The 57 m.y. Middle Fork Plutonic Complex (MFPC) intrudes Paleozoic metasedimentary rocks south of the Farewell Fault zone in the north-central Alaska Range. Though spatially related to the late Cretaceous - Early Tertiary subduction-related Alaska Range batholith, MFPC is more characteristic of an extensional or anorogenic setting. A swarm of basalt, hawaiite and rhyolite dikes east of the complex intruded, and was intruded by, the plutonic rocks. Approximately 30% of the exposed rock in the 125 km[sup 2] complex is hedenbergite - fayalite syenite, [approx equal]20% is peralkalin arfvedsonite-biotite alkali-feldspar granite (AF granite), and [le]20% is pyroxene-olivine-biotite gabbro. The rest is a mixed unit including clinopyroxene-biotite-amphibole diorite, and hornblende-biotite granite (HB granite). K-Ar and Rb-Sr radiometric dating of rock types shows that they are coeval. Their close spatial and temporal relationships led to complex magmatic interactions. Calculated initial [sup 87]Sr/[sup 86]Sr for gabbro and diorite group is around 0.705 to 0.706. HB granites are heterogeneous, but fall mostly around 0.707 to 0.708. Hypersolvus syenites and AF granites form an isochron with initial [sup 87]Sr/[sup 86]Sr of 0.70965. These groupings suggest that at least three different magmas formed the MFPC; scatter of isotopic data reflects mutual contamination and assimilation. Consanguinous hypersolvus syenite and AF granite mineralogy appears to be controlled by fluorine in the magma chamber. Eruptive stratigraphy, as predicted by intrusive history of MFPC, compares favorably with volcanic stratigraphies of peralkaline volcanic systems worldwide, and MFPC may be modelled as the root zone of a peralkaline volcanic system.

  4. Challenges Facing Managers in Managing Conflict in Schools in the South and South Central Regions of Botswana

    ERIC Educational Resources Information Center

    Morake, Nnior Machomi; Monobe, Ratau John; Dingwe, Stephonia

    2011-01-01

    The purpose of this study was to examine the challenges facing managers in managing conflict in schools of South and South Central Regions of Botswana. In this study, the schedule of interview was used to collect empirical data. A random sample of 50 school managers and deputy school managers was selected for interviews. Major findings of the…

  5. 40 CFR 81.253 - South Central Kansas Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 17 2010-07-01 2010-07-01 false South Central Kansas Intrastate Air Quality Control Region. 81.253 Section 81.253 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Air Quality Control Regions § 81.253 South Central Kansas Intrastate Air Quality Control Region....

  6. 40 CFR 81.253 - South Central Kansas Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 18 2013-07-01 2013-07-01 false South Central Kansas Intrastate Air Quality Control Region. 81.253 Section 81.253 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Air Quality Control Regions § 81.253 South Central Kansas Intrastate Air Quality Control Region....

  7. 40 CFR 81.253 - South Central Kansas Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 18 2012-07-01 2012-07-01 false South Central Kansas Intrastate Air Quality Control Region. 81.253 Section 81.253 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Air Quality Control Regions § 81.253 South Central Kansas Intrastate Air Quality Control Region....

  8. 40 CFR 81.253 - South Central Kansas Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 17 2011-07-01 2011-07-01 false South Central Kansas Intrastate Air Quality Control Region. 81.253 Section 81.253 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Air Quality Control Regions § 81.253 South Central Kansas Intrastate Air Quality Control Region....

  9. 40 CFR 81.253 - South Central Kansas Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 18 2014-07-01 2014-07-01 false South Central Kansas Intrastate Air Quality Control Region. 81.253 Section 81.253 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Air Quality Control Regions § 81.253 South Central Kansas Intrastate Air Quality Control Region....

  10. Late Quaternary vegetation and climate history of the central Bering land bridge from St. Michael Island, western Alaska

    NASA Astrophysics Data System (ADS)

    Ager, Thomas A.

    2003-07-01

    Pollen analysis of a sediment core from Zagoskin Lake on St. Michael Island, northeast Bering Sea, provides a history of vegetation and climate for the central Bering land bridge and adjacent western Alaska for the past ≥30,000 14C yr B.P. During the late middle Wisconsin interstadial (≥30,000-26,000 14C yr B.P.) vegetation was dominated by graminoid-herb tundra with willows ( Salix) and minor dwarf birch ( Betula nana) and Ericales. During the late Wisconsin glacial interval (26,000-15,000 14C yr B.P.) vegetation was graminoid-herb tundra with willows, but with fewer dwarf birch and Ericales, and more herb types associated with dry habitats and disturbed soils. Grasses (Poaceae) dominated during the peak of this glacial interval. Graminoid-herb tundra suggests that central Beringia had a cold, arid climate from ≥30,000 to 15,000 14C yr B.P. Between 15,000 and 13,000 14C yr B.P., birch shrub-Ericales-sedge-moss tundra began to spread rapidly across the land bridge and Alaska. This major vegetation change suggests moister, warmer summer climates and deeper winter snows. A brief invasion of Populus (poplar, aspen) occurred ca.11,000-9500 14C yr B.P., overlapping with the Younger Dryas interval of dry, cooler(?) climate. During the latest Wisconsin to middle Holocene the Bering land bridge was flooded by rising seas. Alder shrubs ( Alnus crispa) colonized the St. Michael Island area ca. 8000 14C yr B.P. Boreal forests dominated by spruce ( Picea) spread from interior Alaska into the eastern Norton Sound area in middle Holocene time, but have not spread as far west as St. Michael Island.

  11. Cultural remains in local and regional context on the central Alaska Peninsula: housepits, language, and cultural affinities at Marraatuq after 1000 B.P.

    PubMed

    McClenahan, Patricia L

    2010-01-01

    Professor Dumond's research on the Alaska Peninsula provided information that prior to 1,000 years ago people of both sides of the Alaska Peninsula shared material culture and exhibited subsistence interests that persisted into historic times, During the Late Precontact Era (ca. 1100 A.D. to mid-1700s) these Alutiiq societies shared cultural traits including language, house styles, and material culture with their relatives and neighbors on Kodiak Island. Until recently, few data were available regarding potential variability in house construction techniques, or styles and functions of Alutiiq semi-subterranean houses of this era found on the Alaska Peninsula, This paper provides examples of a few known prehistoric and historic Alaska Peninsula and Kodiak Alutiiq houses and presents previously unreported data from archaeological tests at Marraatuq on the Central Alaska Peninsula, Taken together with Dumond's 1998-1999 field work at Leader Creek and archaeological research on Kodiak Island, the work provides further evidence that interregional interaction was strong during the Late Precontact Era. However, large population centers and ranked political hierarchies probably were not hallmarks of central Alaska Peninsula communities during the Late Precontact Era and historic times as they were on the Kodiak and Aleutian islands. PMID:21495284

  12. Late Mesozoic and Cenozoic Tectonic History of South Central California

    NASA Astrophysics Data System (ADS)

    Engel, A. E. J.; Schultejann, P. A.

    1984-11-01

    The late Mesozoic-Cenozoic history of south central California is punctuated by at least five major tectonic events. The oldest of these involves Late Cretaceous drag folding and thrusting of epizonal shelf sediments westward over and to the north along the rising eastern margin of the Peninsular Ranges Batholith. These overthrusts, with associated drag folds and nappes, form imbricate stacks of metasediments, slices of plutons, and mylonites which overlie a regional core of Cretaceous granitic plutons of the Peninsular Ranges Batholith. A second, distinct kind of epizonal, low-temperature crustal displacement includes an episode of mid-Tertiary detachment faulting and folding. This represents the westerly extension of the detachment terrane of eastern California and western Arizona and Utah, superimposed upon the Cretaceous structural features, The mid-Tertiary motions involve major E-W extension and N-S compressive strain, with formation of east-trending antiformal "core complexes," remarkably parallel to a pervasive set of fold axes and B-lineations formed in the Cretaceous thrusting and folding. All of these features are repeatedly segmented and displaced by step-faulting as sial in the Salton Trough is fragmented and depressed 5 to 10 km below sea level at intervals throughout the Cenozoic. The irregular step-faulted interface of the Peninsular Ranges Batholith and Salton Trough is accentuated by a series of NE to SE striking left-lateral and dipslip faults with displacements of several to 10 kilometers. These appear to both predate and occur during movements along the San Andreas system. Pliocene-Pleistocene right-lateral faulting, a younger extension of the San Andreas displacements north of the Transverse Ranges, has broken and displaced all older structural features, with total net slip in south central California of perhaps 300 km. Total right-lateral slip along the several strands of the San Andreas system are measurable via reconstruction of the mosaic

  13. Bimodal Recurrence Pattern of Tsunami in South Central Chile

    NASA Astrophysics Data System (ADS)

    Kempf, P.; Moernaut, J.; Van Daele, M. E.; Vandoorne, W.; Messens, F.; Vandenberghe, D.; Pino, M.; Urrutia, R.; De Batist, M. A. O.

    2015-12-01

    Establishing the recurrence time of large-scale tsunami is one of the main objectives of paleotsunami research, as it is fundamental for any tsunami risk assessment. Typically, the result is given in form of the mean recurrence time and a standard deviation as a range of uncertainty, assuming a normally distributed recurrence. We present a 5.5 ka long coastal lake paleotsunami record from south central Chile, which contains 17 tsunami deposits, 9 of which were previously unknown. Our record matches all 3 of the historically known tsunami, as well as all of the 5 known paleotsunami in the region without over- or underrepresentation. We used Bayesian age-depth modelling to calculate an age-depth model and extracted recurrence intervals for 16 recurrence intervals. Our findings confirm the previously published mean tsunami recurrence time on the Valdivia seismic segment of ~300 years. However, our analyses show a strongly bimodal recurrence pattern with one mode at ~115 years and the other mode at ~490 years. The least likely recurrence time between the modes is at ~300 years and coincides with the mean recurrence time. The reasons for the bimodal distribution remain speculative. They can be attributed to either spatial variability, e.g. incomplete segment rupture, splay fault rupture, up- or down-dip rupture, or to temporal variability, e.g. megathrust earthquake clustering, earthquake supercycles. Our findings highlight the importance of recognising the variability in tsunami recurrence patterns before using mean recurrence time for tsunami risk assessment.

  14. Sonar Seafloor Exploration within the Central South Atlantic Bight

    NASA Astrophysics Data System (ADS)

    Stubbs, C. C.; Sautter, L. R.; Harris, S. M.

    2006-12-01

    As part of the College of Charleston's Transect Program, research cruises conducted aboard the RV Savannah of the Skidaway Institution of Oceanography and the NOAA Ship Nancy Foster have explored and sampled several localities within the central portion of the South Atlantic Bight, the continental shelf region between Florida and Cape Hatteras, NC. Klein sidescan and Kongsberg multibeam sonar arrays collected seafloor images and bathymetric data that were processed by CofC undergraduate geology researchers using Caris HIPS/SIPS software. Several of the data sets have been ground-truthed using sediment grabs, footage from ROV cameras and SCUBA videography. Two of the prominent seafloor features discovered are (1) an outcropping hard-ground shelf-edge structure approximately 650 by 150 m, with 10 m relief. It is oriented parallel to shore in water depths of 60 m. Possible geological and biological influences on the structure's origin and morphology are being explored; and (2) a meandering river channel located on the mid-shelf, where water depth is approximately 22 m. Rock and sediment samples as well as video documentation of this feature reveal a channel with 1.5 m of relief, cut into the hard-ground, and includes coarse sands and abundant river pebbles. Additional shelf hard-ground features will be presented.

  15. Metamorphosed melange in the central Piedmont of South Carolina

    SciTech Connect

    Mittwede, S.K.; Maybin, A.H. III )

    1989-09-01

    The Enoree melange is exposed in the central Piedmont of South Carolina near the boundary between the Piedmont and Carolina terranes. The melange is composed of ultramafic and mafic blocks in a highly deformed matrix of biotite-feldspar-quartz gneiss which has a composition consistent with a felsic-to-intermediate volcanic precursor. The mafic and ultramafic blocks are separated chemically and petrographically into four compositional groups: metagabbro-clinopyroxenite, websterite, orthopyroxenite, and metasomatized (steatitized) orthopyroxenite. Based on their chemistry and mineralogy, the blocks are clearly exotic relative to their metavolcaniclastic( ) matrix and likely originated as parts of a plutonic suite from the basal or forward part of the Carolina arc terrane. If the Piedmont terrane-Carolina terrane boundary is a continent-arc suture, then the Enoree melange probably formed in the accretionary prism at this convergent margin. The matrix gneisses are interpreted as reworked volcanic debris shed by the Carolina arc terrane edifice and accumulated as graywacke in the accretionary deposits. West-vergent structures in the matrix suggest that the melange was emplaced to its present tectonostratigraphic position either during docking of the Carolina terrane or during widespread Alleghenian thrusting.

  16. Late Holocene megathrust earthquakes in south central Chile

    NASA Astrophysics Data System (ADS)

    Garrett, Ed; Shennan, Ian; Gulliver, Pauline; Woodroffe, Sarah

    2013-04-01

    A lack of comprehensive understanding of the seismic hazards associated with a subduction zone can lead to inadequate anticipation of earthquake and tsunami magnitudes. Four hundred and fifty years of Chilean historical documents record the effects of numerous great earthquakes; however, with recurrence intervals between the largest megathrust earthquakes approaching 300 years, seismic hazard assessment requires longer chronologies. This research seeks to verify and extend historical records in south central Chile using a relative-sea level approach to palaeoseismology. Our quantitative, diatom-based approaches to relative sea-level reconstruction are successful in reconstructing the magnitude of coseismic deformation during recent, well documented Chilean earthquakes. The few disparities between my estimates and independent data highlight the possibility of shaking-induced sediment consolidation in tidal marshes. Following this encouraging confirmation of the approach, we quantify land-level changes in longer sedimentary records from the centre of the rupture zone of the 1960 Valdivia earthquake. Here, laterally extensive marsh soils abruptly overlain by low intertidal sediments attest to the occurrence of four megathrust earthquakes. Sites preserve evidence of the 1960 and 1575 earthquakes and we constrain the timing of two predecessors to 1270 to 1410 and 1050 to 1200. The sediments and biostratigraphy lack evidence for the historically documented 1737 and 1837 earthquakes.

  17. Water movement in till of east-central South Dakota

    SciTech Connect

    Craven, S.J.; Ruedisili, L.C.; Barari, A.

    1985-01-01

    Factors that control the flow of water through till are poorly understood. Hydrographic analyses, field hydraulic conductivity measurements, and major-ion sampling were conducted on weathered and unweathered tills at 22 sites in east-central South Dakota. Water from a buried outwash aquifer was also chemically analyzed and carbon age dated. The upper part of most till has been weathered and exhibits extensive secondary permeability. Hydraulic conductivity values range from 10/sup -7/ to 10/sup -4/ cm/sec; typically 10 to 200 times higher than the hydraulic conductivity of unweathered till. Hydraulic gradients within weathered tills average seven times lower than within unweathered till. Water infiltrating below plant roots is believed to principally recharge and discharge the weathered till. Total dissolved solids were significantly higher in the weathered till than in the unweathered till. Water extracted from unweathered till is, in turn, up to three time higher in major-ion concentrations than water from the underlying outwash aquifer. Carbon-14 age dates from outwash aquifer water exceed 9000 years before present. Results indicate that Tittle to no water passes from the weathered till through the unweathered till into the buried outwash aquifer. Discharge from the weathered till is hypothesized to be primarily local lateral flow to sloughs, streams and ponds, combined with evapotranspiration losses during periods of high water table.

  18. Sparta sandstones: future exploration potential in south-central Louisiana

    SciTech Connect

    Lemoine, R.C.; Moslow, T.F.; Sassen, R.; Ferrell, R.E.

    1989-03-01

    The middle Eocene Sparta Formation is an important exploration objective within the prolific Eocene-Oligocene trend of south-central Louisiana. Cumulative production from 20 multiple-reservoir fields in the trend exceeds 269 million bbl of crude, 50 million bbl of condensate, and 1.5 billion ft/sup 3/ of gas. Additional reservoirs include the lower Eocene Wilcox, upper Eocene Cockfield, and Oligocene Frio Formations. This trend, coincident with the location of the Lower Cretaceous carbonate shelf edge, represents a series of unstable progradational clastic shelf margins. Principal structural traps are rollover anticlines, associated with down-to-the-basin growth faults, and salt domes. Recent Sparta production is associated with progradational barrier island complexes. Storm washover fan sandstones (22% porosity, 324 md permeability), tidal-inlet channel sandstones (20% porosity, 140 md permeability), and upper shoreface sandstones (19% porosity, 113 md permeability) represent the optimum-quality reservoir facies. Organic-rich basinal shales are source rocks for crude oil downdip from production where they are thermally mature. Lateral migration best explains emplacement of hydrocarbons in reservoirs.

  19. Water quality of Somerville Lake, south-central Texas

    USGS Publications Warehouse

    McPherson, Emma; Mendieta, H.B.

    1983-01-01

    Lake Somerville in south-central Texas has excellent water for municipal, industrial, and agricultural use. The total dissolved solids of the water averaged 220 milligrams per liter during a study from 1975-80. This shallow lake has a mean depth of 14 feet. The average annual inflow and discharge is greater than the volume of the lake. These two factors, along with wind action and the cooling of surface water during both summer and winter keep the lake well mixed and aerated. Even in summer the dissolved oxygen concentrations at the bottom of the lake usually were in excess of 50 percent of saturation. Dissolved iron concentrations are less than 50 micrograms per liter and dissolved manganese concentrations are under 40 micrograms per liter. These small concentrations are largely attributable to year-round oxygenated water. Homogeneous or near homogeneous concentrations of total phosphorus and inorganic nitrogen can occur at any time of the year throughout the lake. Dissolved chloride concentrations averaged 43 milligrams per liter and dissolved sulfate concentrations averaged 63 milligrams per liter. The total hardness of the water averaged about 110 milligrams per liter, placing it in the moderately hard classfication. (USGS)

  20. South Central Coast Cooperative Aerometric Monitoring Program (SCCCAMP)

    SciTech Connect

    Dabberdt, W.F.; Viezee, W.

    1987-09-01

    The SCCCAMP field measurement program, conducted 3 September to 7 October 1985, is the most comprehensive mesoscale photochemical study of its type ever undertaken. The study area encompasses 2 x 10/sup 4/ km/sup 2/ of coastal and interior south-central California including the Santa Barbara Channel. A review of earlier experimental and analytical studies in the area is followed by the organizational framework and planning for this cooperative program. The experimental design and measurement systems are described. Existing ground-based meteorological and air pollution networks were supplemented by additional surface aerometric stations, dual Doppler radars, rawinsondes, and a network of Doppler acoustic profilers. Airborne measurement platforms included one dual-channel lidar, three aerometric sampling aircraft, /sup 3/ and a meteorological research aircraft. Gas tracer tests included 4-h releases of three perfluorocarbon gas tracers. Tracer measurements were made over two-day periods at 50 surface locations and aloft by aircraft with a near-realtime two-trap chromatographic system. Four multi-day intensive operational periods (IOP) are described, and illustrative results from one IOP are presented when extremely high ozone concentrations were observed at ground level (230 ppb) and aloft (290 ppb). The availability of the composite data base is indicated.

  1. South Central Coast Cooperative Aerometric Monitoring Program (SCCCAMP).

    NASA Astrophysics Data System (ADS)

    Dabberdt, Waiter F.; Viezee, William

    1987-09-01

    The SCCCAMP field measurement program, conducted 3 September to 7 October 1985, is the most comprehensive mesoscale photochemical study of its type ever undertaken. The study area encompasses 2 × 104 km2 of coastal and interior south-central California including the Santa Barbara Channel. A review of earlier experimental and analytical studies in the area is followed by the organizational framework and planning for this cooperative program. The experimental design and measurement systems are described. Existing ground-based meteorological and air pollution networks were supplemented by additional surface aerometric stations, dual Doppler radars, rawinsondes, and a network of Doppler acoustic profilers. Airborne measurement platforms included one dual-channel lidar, three aerometric sampling aircraft, and a meteorological research aircraft. Gas tracer tests included 4-h releases of three perfluorocarbon gas tracers. Tracer measurements were made over two-day periods at 50 surface locations and aloft by aircraft with a near-realtime two-trap chromatographic system. Four multi-day intensive operational periods (IOP) are described, and illustrative results from one IOP are presented when extremely high ozone concentrations were observed at ground level (230 ppb) and aloft (290 ppb). The availability of the composite data base is indicated.

  2. Quaternary tectonic setting of South-Central coastal California

    USGS Publications Warehouse

    Lettis, William R.; Hanson, Kathryn L.; Unruh, Jeffrey R.; McLaren, Marcia; Savage, William U.; Keller, Margaret A.

    2004-01-01

    Recent geodetic, geologic, and seismologic studies show that the south-central coast of California is a region of active Quaternary deformation. Northeast-directed crustal shortening is occurring in a triangular-shaped region between the Hosgri-San Simeon fault system on the west, the Southern Coast Ranges on the northeast, and the western Transverse Ranges on the south. We informally call this region the Los Osos domain. In this study, we conducted detailed geological, seismological, and geophysical investigations to characterize the nature and rates of deformation in the domain. Locations of active and potentially active faults and folds are compiled at a scale of 1:250,000 for the entire domain based primarily on onshore geologic data and offshore geophysical data. Crustal shortening in the domain is accommodated by a series of prominent northwest-trending reverse faults and localized folding. The reverse faults separate distinct structural blocks that have little or no internal deformation. Hangingwall blocks are being uplifted at rates of up to 0.2 mm/yr. Footwall blocks are either static or slowly subsiding at rates of 0.1 mm/yr or less, except for localized areas of concentrated subsidence directly adjacent to some faults. The cumulative rate of crustal shortening is about 1 to 2 mm/yr across the northern part of the domain based on observed geologic deformation. Cumulative shortening across the central and southern parts of the domain is poorly constrained by geologic data and may approach 2 to 3 mm/yr. Historical and instrumental seismicity generally are spatially associated with the uplifted blocks and bordering reverse faults to depths of about 10 km. Together with near-surface geological data and deeper crustal geophysical imaging that show high-angle faulting, the seismicity data indicate that the reverse faults probably extend to the base of the seismogenic crust. The base of the seismogenic crust may correspond with a mid-crustal detachment or

  3. Analysis of Regionally Detected Icequakes Using the STEEP Network, South-Central AK

    NASA Astrophysics Data System (ADS)

    O'Neel, S.; Leblanc, L.; Larsen, C.; Truffer, M.; Hansen, R.; Rupert, N.; Pavlis, G.; None, N.

    2007-12-01

    Glaciers produce seismic energy that is detectable from local to teleseismic distances. Glaciolgical processes including calving, surface crevassing, basal sliding and other, yet unresolved source processes are capable of producing recordable seismicity. Twenty-two broadband sensors deployed in south-central Alaska during the SainT Elias TEctonics and Erosion Project (STEEP) provide an excellent means to study glacier-generated seismicity at regional distances. These instruments surround over 7500 km2 of glacier area including the Bering Glacier, Bagley Icefield and the tidewater calving glaciers of Icy Bay (Yahtse, Guyot, Tyndal). Our analysis shows that icequakes nominally occur several times hourly, and can be separated from tectonic seismicity using their unique spectral characteristics and hypocenter locations. The events typically propagate over 50-75 km distances, but occasionally are recorded at stations over 150 km away from the energy source. Hypocenters for more than 1000 events were manually calculated through a 26-day interval during October 2006, and suggest that a majority of the icequakes are associated with calving at tidewater glaciers that terminate in Icy Bay. Events with similar time and frequency domain characteristics also occur at locations away from calving fronts, but less often, and their mechanical origin remains undetermined. Automated detections from a frequency domain event detector exhibit strong correlation with the handpicked time series, and extend our analysis to all available data collected during 2006. We present the time distribution of several categories of icequakes and compare these distributions to environmental variables such as precipitation, temperature and tides to explore potential forcing for observed variability in icequake occurrence.

  4. 2009 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    McGimsey, Robert G.; Neal, Christina A.; Girina, Olga A.; Chibisova, Marina; Rybin, Alexander

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest, and reports of unusual activity at or near eight separate volcanic centers in Alaska during 2009. The year was highlighted by the eruption of Redoubt Volcano, one of three active volcanoes on the western side of Cook Inlet and near south-central Alaska's population and commerce centers, which comprise about 62 percent of the State's population of 710,213 (2010 census). AVO staff also participated in hazard communication and monitoring of multiple eruptions at ten volcanoes in Russia as part of its collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

  5. Geochemistry of saline lakes of the northeastern Yukon Flats, east central Alaska

    NASA Astrophysics Data System (ADS)

    Hawkins, D. B.

    1985-01-01

    Above the Arctic Circle in the Yukon Flats of northeastern Alaska, shallow, brackish water ponds are rimmed with evaporite minerals such as trona (NaHCO3Na2CO3). These ponds form in an area of Alaska characterized by an extreme continental climate with about six inches of precipitation annually. Evaporite formation occurs because evaporation exceeds inflow. The hydrogeochemistry of the waters of the Yukon Flats was investigated to determine the origin of the ponds and evaporite minerals. Evaporation of the freshwater lakes will first precpitate calcite and ultimately form trona. The change in relative concentrations of Ca(+2), HCO3, and SO4 in going from river water to lake water is critical and indicates that sulfate reduction accompanied by bicarbonate formation is an essential process that produces an excess of HCO3 over CA(+2).

  6. Distribution and characteristics of metamorphic belts in the south- eastern Alaska part of the North American Cordillera

    USGS Publications Warehouse

    Brew, D.A.; Himmelberg, G.R.; Loney, R.A.; Ford, A.B.

    1992-01-01

    The Cordilleran orogen in south-eastern Alaska includes 14 distinct metamorphic belts that make up three major metamorphic complexes, from east to west: the Coast plutonic-metamorphic complex; the Glacier Bay-Chichagof plutonic-metamorphic complex; and the Chugach plutonic-metamorphic complex. Each of these complexes is related to a major subduction event. The metamorphic history of the Coast complex is lengthy and is related to the Late Cretaceous collision of the Alexander and Wrangellia terranes and the Gravina overlap assemblage to the west against the Stikine terrane to the east. The metamorphic history of the Glacier Bay-Chichagof complex is relatively simple and is related to the roots of a Late Jurassic to late Early Cretaceous island arc. The metamorphic history of the Chugach is complicated and developed during and after the Late Cretaceous collision of the Chugach terrane with the Wrangellia and Alexander terranes. -from Authors

  7. Baseline channel morphology and bank erosion inventory of South Fork Campbell Creek at Campbell Tract, Anchorage, Alaska, 1999 and 2000

    USGS Publications Warehouse

    Curran, Janet H.

    2001-01-01

    South Fork Campbell Creek drains largely undeveloped land in Anchorage, Alaska, but supports heavy use near the Bureau of Land Management (BLM) Campbell Tract facility for recreation and environmental education. To help assess the impacts of human activities in the basin on biological communities, particularly aquatic and terrestrial biota, morphological changes to the channel bed and banks were monitored for 2 years. Erosion conditions and rates of change were measured and 11 transects were surveyed in three reaches of Campbell Creek near the BLM Campbell Creek Science Center in 1999. Repeat measurements at these 33 transects in 2000 documented noticeable differences between horizontal or vertical channel position at eight transects. Repeat measurements of 51 erosion pins at the survey transects provided details of bank erosion between the 2 years. Annual erosion rates at the erosion pins ranged from 0.81 foot per year of erosion to 0.16 foot per year of deposition.

  8. Ground-water investigation at the alluvial fan of the South Fork River, Anchorage, Alaska: results of test drilling, 1976

    USGS Publications Warehouse

    Dearborn, Larry L.

    1977-01-01

    In late 1976, at Anchorage, Alaska, a ground-water exploration well was drilled to a depth of 487 feet on the South Fork Eagle River fan near the confluence with the mainstream. The well penetrated four sand and gravel strata of low water-yielding capacity and extended 37 ft into metamorphic bedrock. Earth water-bearing stratum was pumped for several hours, and the best aquifer yield was found to be 1.7 gal/min/ft of drawdown. These test results support the conclusion, previously inferred from drilling data at a nearby test hole drilled in 1973, that there are no confined aquifers of large yield in the subsurface at this locality. (Woodard-USGS)

  9. Shallow-water habitat use by Bering Sea flatfishes along the central Alaska Peninsula

    NASA Astrophysics Data System (ADS)

    Hurst, Thomas P.

    2016-05-01

    Flatfishes support a number of important fisheries in Alaskan waters and represent major pathways of energy flow through the ecosystem. Despite their economic and ecological importance, little is known about the use of habitat by juvenile flatfishes in the eastern Bering Sea. This study describes the habitat characteristics of juvenile flatfishes in coastal waters along the Alaska Peninsula and within the Port Moller-Herendeen Bay system, the largest marine embayment in the southern Bering Sea. The two most abundant species, northern rock sole and yellowfin sole, differed slightly in habitat use with the latter occupying slightly muddier substrates. Both were more common along the open coastline than they were within the bay, whereas juvenile Alaska plaice were more abundant within the bay than along the coast and used shallow waters with muddy, high organic content sediments. Juvenile Pacific halibut showed the greatest shift in distribution between age classes: age-0 fish were found in deeper waters (~ 30 m) along the coast, whereas older juveniles were found in the warmer, shallow waters within the bay, possibly due to increased thermal opportunities for growth in this temperature-sensitive species. Three other species, starry flounder, flathead sole, and arrowtooth flounder, were also present, but at much lower densities. In addition, the habitat use patterns of spring-spawning flatfishes (northern rock sole, Pacific halibut, and Alaska plaice) in this region appear to be strongly influenced by oceanographic processes that influence delivery of larvae to coastal habitats. Overall, use of the coastal embayment habitats appears to be less important to juvenile flatfishes in the Bering Sea than in the Gulf of Alaska.

  10. Paleoclimatic significance of chemical weathering in loess-derived paleosols of subarctic central Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Ager, T.A.; Skipp, G.; Beann, J.; Budahn, J.; McGeehin, J.P.

    2008-01-01

    Chemical weathering in soils has not been studied extensively in high-latitude regions. Loess sequences with modern soils and paleosols are present in much of subarctic Alaska, and allow an assessment of present and past chemical weathering. Five sections were studied in detail in the Fairbanks, Alaska, area. Paleosols likely date to mid-Pleistocene interglacials, the last interglacial, and early-to-mid-Wisconsin interstadiale. Ratios of mobile (Na, Ca, Mg, Si) to immobile (Ti or Zr) elements indicate that modern soils and most interstadial and interglacial paleosols are characterized by significant chemical weathering. Na2O/TiO2 is lower in modern soils and most paleosols compared to parent loess, indicating depletion of plagioclase. In the clay fraction, smectite is present in Tanana and Yukon River source sediments, but is absent or poorly expressed in modern soils and paleosols, indicating depletion of this mineral also. Loss of both plagioclase and smectite is well expressed in soils and paleosols as lower SiO 2/TiO2. Carbonates are present in the river source sediments, but based on CaO/TiO2, they are depleted in soils and most paleosols (with one exception in the early-to-mid-Wisconsin period). Thus, most soil-forming intervals during past interglacial and interstadial periods in Alaska had climatic regimes that were at least as favorable to mineral weathering as today, and suggest boreal forest or acidic tundra vegetation. ?? 2008 Regents of the University of Colorado.

  11. Seasonal and Latitudinal Variations in Dissolved Methane from 42 Lakes along a North-South Transect in Alaska

    NASA Astrophysics Data System (ADS)

    Sepulveda-Jauregui, A.; Walter Anthony, K. M.; Martinez-Cruz, K. C.; Anthony, P.; Thalasso, F.

    2013-12-01

    Armando Sepulveda-Jauregui,* Katey M. Walter Anthony,* Karla Martinez-Cruz,* ** Peter Anthony,* and Frederic Thalasso**. * Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, Alaska. ** Biotechnology and Bioengineering Department, Cinvestav, Mexico city, D. F., Mexico. Northern lakes are important reservoirs and sources to the atmosphere of methane (CH4), a potent greenhouse gas. It is estimated that northern lakes (> 55 °N) contribute about 20% of the total global lake methane emissions, and that emissions from these lakes will increase with climate warming. Temperature rise enhances methane production directly by providing the kinetic energy to methanogenesis, and indirectly by supplying organic matter from thawing permafrost. Warmer lakes also store less methane since methane's solubility is inversely related to temperature. Alaskan lakes are located in three well-differentiated permafrost classes: yedoma permafrost with high labile carbon stocks, non-yedoma permafrost with lower carbon stocks, and areas without permafrost, also with generally lower carbon stocks. We sampled dissolved methane from 42 Alaskan lakes located in these permafrost cover classes along a north-south Alaska transect from Prudhoe Bay to the Kenai Peninsula during open-water conditions in summer 2011. We sampled 26 of these lakes in April, toward the end of the winter ice-covered period. Our results indicated that the largest dissolved methane concentrations occurred in interior Alaska thermokarst lakes formed in yedoma-type permafrost during winter and summer, with maximal concentrations of 17.19 and 12.76 mg L-1 respectively. In these lakes, emission of dissolved gases as diffusion during summer and storage release in spring were 18.4% and 17.4% of the annual emission budget, while ebullition (64.2 %) comprised the rest. Dissolved oxygen was inversely correlated with dissolved methane concentrations in both seasons; the

  12. Brookian sequence well log correlation sections and occurrence of gas hydrates, north-central North Slope, Alaska

    USGS Publications Warehouse

    Lewis, Kristen A.; Collett, Timothy S.

    2013-01-01

    Gas hydrates are naturally occurring crystalline, ice-like substances that consist of natural gas molecules trapped in a solid-water lattice. Because of the compact nature of their structure, hydrates can effectively store large volumes of gas and, consequently, have been identified as a potential unconventional energy source. First recognized to exist geologically in the 1960s, significant accumulations of gas hydrate have been found throughout the world. Gas hydrate occurrence is limited to environments such as permafrost regions and subsea sediments because of the pressure and temperature conditions required for their formation and stability. Permafrost-associated gas hydrate accumulations have been discovered in many regions of the Arctic, including Russia, Canada, and the North Slope of Alaska. Gas hydrate research has a long history in northern Alaska. This research includes the drilling, coring, and well log evaluation of two gas hydrate stratigraphic test wells and two resource assessments of gas hydrates on the Alaska North Slope. Building upon these previous investigations, this report provides a summary of the pertinent well log, gas hydrate, and stratigraphic data for key wells related to gas hydrate occurrence in the north-central North Slope. The data are presented in nine well log correlation sections with 122 selected wells to provide a regional context for gas hydrate accumulations and the relation of the accumulations to key stratigraphic horizons and to the base of the ice-bearing permafrost. Also included is a well log database that lists the location, available well logs, depths, and other pertinent information for each of the wells on the correlation section.

  13. Mantle Xenoliths from Central and South Vietnam: Petrology and Geochemistry

    NASA Astrophysics Data System (ADS)

    Hauzenberger, Christoph; Konzett, Juergen; Nguyen, Hoang; Nguyen, Khoi

    2014-05-01

    Mantle xenoliths, spinel lherzolites and subordinate amounts of spinel harzburgites and pyroxenites, are commonly found in alkali basalts from south-central Vietnam. The basalts are part of widespread Neogene volcanism found in southern China and Indochina regions. Samples from different localities between the cities of Ban Me Thuot and Saigon were recovered. In addition one xenolith sample from an off-shore volcano SE of Ho Chi Minh City in the South China Sea was investigated. The mineral assemblage in most samples consists of the simple lherzolitic mineral assemblage Ol-Opx-Cpx-Sp. The Ol, Cpx and Opx crystals are equigranular while Sp occurs usually as smaller sized intersertal phase or as partly oriented inclusions in Cpx. Cpx II occurs in some samples as recrystallized "spongy rim" around Cpx I. Cpx I has a a very uniform composition between different samples with a typical XMg (=Mg/(Mg+Fe2+) of 0.92 to 0.98, a XNa (=Na/(Na+Ca) of 0.10 to 0.16, a Cr2O3 content of 0.6-0.9 wt. .% and Al2O3 values of c. 6 to 8 wt.%. Cpx II has a lower XNa and Al content as well as higher XMg and Cr content compared to Cpx I. Orthopyroxene typically has a XMg of c. 0.90 to 0.93. The XMg values for Ol differ slightly between different samples but are within 0.84 to 0.94. Spinel grains have a variable composition with XMg from 0.65 to 0.92 and XCr (Cr/Cr+Al+Fe3+) of 0.08 to 0.25. The use of the Cpx-Opx thermometer (BREY & KOEHLER, 1990) and the Al and Cr in Ol thermometer (DE HOOG et al., 2010) allowed to constrain the temperature with 800 to 1100 °C. Trace and rare earth element composition of Cpx was determined by LA-ICPMS. While most Cpx compositions are slightly depleted in LREE, typical for average depleted mantle compositions, some samples are strongly enriched in LREE indicating mantle metasomatic processes. The sample displaying the highest level of LREE enrichment in Cpx has the lowest calculated temperature (T = c. 800°C) and the highest Ni content in olivine (3000 ppm

  14. Characterization of the mississippian chat in South-central Kansas

    USGS Publications Warehouse

    Watney, W.L.; Guy, W.J.; Byrnes, A.P.

    2001-01-01

    To understand production from low resistivity-high porosity Mississippian chat reservoirs in south-central Kansas it is necessary to understand the nature of deposition and diagenesis, how tectonics is a factor, the lithofacies controls on petrophysical properties, and log response to these properties. The initial mudstones to sponge-spicule wacke-packstones were deposited in transgressive-regressive (T-R) cycles on a shelf to shelf margin setting, resulting in a series of shallowing-upward cycles. Sponge-spicule content appears to increase upward with increasing cycle thickness. After early silicification, inter- and post-Mississippian subaerial exposure resulted in further diagenesis, including sponge-spicule dissolution, vuggy porosity development in moldic-rich rocks, and autobrecciation. Meteoric water infiltration is limited in depth below the exposure surface and in distance downdip into unaltered, cherty Cowley Formation facies. Areas of thicker preserved chat and increased diagenesis can be correlated with structural lineaments and, in some areas, with recurrent basement block movement. Combination of folding or block fault movement prior to or during development of the basal Pennsylvanian unconformity, sponge-spicule concentration, and possibly thickness of overlying bioclastic wacke-grainstones resulted in variable reservoir properties and the creation of pods of production separated by nonproductive cherty dolomite mudstones. These events also resulted in alteration of the depositional cycles to produce a series of lithofacies that exhibit unique petrophysical properties. From bottom to top in a complete cycle seven lithofacies are present: (1) argillaceous dolomite mudstone, (2) argillaceous dolomite mudstone that has chert nodules, (3) clean dolomite mudstone that has nodular chert, (4) nodular to bedded chert, (5) autoclastic chert, (6) autoclastic chert that has clay infill, and (7) bioclastic wacke-grainstone. The uppermost cycle was terminated by

  15. Snowflake Size Distribution Measurements in South Central Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Tokay, A.; Bringi, V. N.; Huang, G.; Schoenhuber, M.; Bashor, P. G.; Hudak, D.; Jackson, G. S.; Petersen, W. A.

    2007-05-01

    In support of NASA's Global Precipitation Measurement (GPM) mission ground validation program, NASA's two laser optical disdrometers (Parsivel) and Colodaro State University (CSU) two-dimensional video disdrometer (2dvd) were deployed to a well-equipped precipitation observation site in South Central Ontario, Canada. The instruments were collocated and have been operating since late November 2006. So far, there has been numerous lake effect and synoptic winter storms over the site. In one event, parsivel disdrometers recorded 50 cm of snowfall. In addition, there have been at least 10 storms where the snow accumulation exceeded 4 cm. The leading objective of this study was to compare the parsivel and 2dvd size and fall velocity measurements for selected cases and relate the findings to the physical processes within and below the cloud. Unlike 2dvd, parsivel measures the maximum dimension of the snowflake in a single plane, while the fall velocity is calculated from the duration of the flake within the laser beam. The 2dvd samples the same flake in two planes from which fall velocity is obtained. The 2dvd also measures the maximum width and height in both planes. At the time of this abstract, two parsivels and 2dvd were operated nearly continuously for almost three months and preliminary data analysis is encouraging. The field site, which is known as Centre for Atmospheric Research Experiments (CARE), is an atmospheric research facility operated by the Air Quality Research Branch of the Meteorological Service of Canada and is located 80 km north of Toronto, Ontario, Canada in a rural agricultural and forested region. During the past three winters, a field campaign was conduced in support of Canadian CloudSat/CALIPSO validation project (c3vp). However, 2006-07 winter was the first since the satellites were in orbit. The coordinated efforts of aircraft missions over the CARE facility during the Intensive Operation Periods will enhance our understanding of cold cloud

  16. Hydrology of the Oakley Fan Area, south-central Idaho

    USGS Publications Warehouse

    Young, H.W.; Newton, G.D.

    1989-01-01

    The Oakley Fan area is a broad, crescent-shaped lowland along the southern margin of the Snake River Plain in south-central Idaho. Intensive groundwater development for irrigation has resulted in rapid water-level declines and, as a consequence, designation by the State of four Critical Groundwater Areas. Principal aquifers are in limestone, rhyolite, basalt, and alluvium. Annual water-level declines range from 3 ft to about 5 ft. Recharge to the groundwater system is from infiltration of surface water used for irrigation, precipitation on the surrounding mountains, infiltration of localized runoff, and upward movement of thermal water. Groundwater pumpage during the period 1979-84 averaged 173,000 acre-ft/yr. Surface and groundwater is predominantly a calcium bicarbonate type with variable concentrations of dissolved solids. Comparisons of silica and chloride concentrations and isotopic composition of groundwater were useful in determining areal extent of aquifers and movement of groundwater. A three-dimensional mathematical model of the Oakley Fan area was developed. The aquifer system was simulated in three phases: (1) Average 1979-84 hydrologic conditions, (2) 1910 hydrologic conditions, and (3) 1910-84 hydrologic conditions. Model simulation indicated that, for the period 1945-79, subsurface outflow declined from 327,000 acre-ft/yr to 215,000 acre-ft/yr. Simulated groundwater pumpage during the period 1945-79 was 3,000,000 acre-ft; simulated change in storage was 250,000 acre-ft. Simulations with the model approximate natural conditions and probably can be used to evaluate future changes in the hydrologic system.

  17. Diabetes in South and Central America: an update.

    PubMed

    Aschner, Pablo; Aguilar-Salinas, Carlos; Aguirre, Loreto; Franco, Laercio; Gagliardino, Juan Jose; de Lapertosa, Sylvia Gorban; Seclen, Segundo; Vinocour, Mary

    2014-02-01

    The estimated population of the South and Central America (SACA) Region is 467.6 million and 64% is in the age range of 20-79 years but the population pyramid and age distribution are changing. The average prevalence of diabetes in the Region is 8.0% and is expected to reach 9.8% by the year 2035. Prevalence is much lower in rural settings than in urban and the differences attributed to lifestyle changes may be a target for intervention. The indigenous population is a particularly vulnerable group needing special attention. On average, 24% of the adult cases with diabetes are undiagnosed but in some countries this is still as high as 50%. Health expenditure due to diabetes in the Region is around 9% of the global total. Inadequate glycemic control, defined as HbA1c >7%, is a strong predictor of chronic complications which increase resource use in the Region and less than half of the patients enrolled in diabetes care programmes are at target. Fifty percent or more of the adult population is overweight/obese and around one third of the adult population has metabolic syndrome using regional cutoffs for waist circumference. The number of people with IGT is almost equal to those with diabetes presenting an additional challenge for prevention. Children with type 1 diabetes represent only 0.2% of the total population with diabetes but the incidence may be increasing. In many places they have limited access to insulin, and even when available, it is not used appropriately. The available epidemiological data provide the background to act in developing national diabetes programmes which integrate diabetes care with cardiovascular prevention and promote diabetes prevention as well. PMID:24439209

  18. Enhanced recharge and karst, Edwards aquifer, south central Texas

    SciTech Connect

    Hammond, W.W. Jr. . Center for Water Research)

    1993-02-01

    Enhanced recharge is a water management strategy which can add significant quantities of ground water to the available water resources of the San Antonio region by utilizing the immense storage capacity of the unconfined zone of the Edwards aquifer. The Edwards aquifer presently is the sole source of water for a population of over 1,200,000, meeting public supply, industrial, and irrigation demands over a wide area of south central Texas. Valdina Farms Sinkhole is located adjacent to Seco Creek in Medina County and is in the recharge zone of the aquifer. Initial studies indicated that the sinkholes was capable of taking flood flows from Seco Creek and functioning as a recharge structure. Stream channels in the cavern system associated with Valdina Farms Sinkhole were incised into cave deposits and flood debris was present in the caverns at some distance from the sinkhole. Chemical analyses of samples of water from the cave and from nearby wells showed nitrate concentrations that decreased with distance from the cavern. Gradient of the potentiometric surface in the vicinity of the cave was very low, indicating high values of hydraulic conductivity for the aquifer. Based on evidence from these field studies a dam was constructed in 1982 on Seco Creek and a flood diversion channel was excavated to the sinkhole. Reservoir capacity is 2 acre-feet and design recharge rate is 3.8-6.7 m[sup 3]/sec. Annual recharge at the sinkhole has varied from 0 during periods of low runoff to 12,915 acre-feet.

  19. Stratigraphy and palaeoclimatic significance of Late Quaternary loess-palaeosol sequences of the Last Interglacial-Glacial cycle in central Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Ager, T.A.; Bettis, E. Arthur, III; McGeehin, J.; Been, J.M.; Beget, J.E.; Pavich, M.J.; Stafford, Thomas W., Jr.; Stevens, D.A.S.P.

    2003-01-01

    Loess is one of the most widespread subaerial deposits in Alaska and adjacent Yukon Territory and may have a history that goes back 3 Ma. Based on mineralogy and major and trace element chemistry, central Alaskan loess has a composition that is distinctive from other loess bodies of the world, although it is quartz-dominated. Central Alaskan loess was probably derived from a variety of rock types, including granites, metabasalts and schists. Detailed stratigraphic data and pedologic criteria indicate that, contrary to early studies, many palaeosols are present in central Alaskan loess sections. The buried soils indicate that loess sedimentation was episodic, or at least rates of deposition decreased to the point where pedogenesis could keep ahead of aeolian input. As in China, loess deposition and pedogenesis are likely competing processes and neither stops completely during either phase of the loess/soil formation cycle. Loess deposition in central Alaska took place before, and probably during the last interglacial period, during stadials of the mid-Wisconsin period, during the last glacial period and during the Holocene. An unexpected result of our geochronological studies is that only moderate loess deposition took place during the last glacial period. Our studies lead us to conclude that vegetation plays a key role in loess accumulation in Alaska. Factors favouring loess production are enhanced during glacial periods but factors that favour loess accumulation are diminished during glacial periods. The most important of these is vegetation; boreal forest serves as an effective loess trap, but sparsely distributed herb tundra does not. Thus, thick accumulations of loess should not be expected where tundra vegetation was dominant and this is borne out by modern studies near the treeline in central Alaska. Much of the stratigraphic diversity of North American loess, including that found in the Central Lowlands, the Great Plains, and Alaska is explained by a new

  20. A 2000 year varve-based climate record from the central Brooks Range, Alaska

    SciTech Connect

    Bird, B.W.; Abbott, M.B.; Finney, B.P.; Kutchko, Barbara

    2009-01-01

    Varved minerogenic sediments from glacial-fed Blue Lake, northern Alaska, are used to investigate late Holocene climate variability. Varve thickness measurements track summer temperature recorded at Atigun Pass, located 41 km east at a similar elevation (r2 = 0.31, P = 0.08). Results indicate that climate in the Brooks Range from 10 to 730 AD (varve year) was warm with precipitation inferred to be higher than during the twentieth century. The varve-temperature relationship for this period was likely compromised and not used in our temperature reconstruction because the glacier was greatly reduced, or absent, exposing sub-glacial sediments to erosion from enhanced precipitation.

  1. Coordination and establishment of centralized facilities and services of the University of Alaska ERTS survey of the Alaskan environment

    NASA Technical Reports Server (NTRS)

    Belon, A. E. (Principal Investigator); Miller, J. M.

    1973-01-01

    The author has identified the following significant results. The objective of this project is to provide a focus for the entire University of Alaska ERTS-1 effort (12 projects covering 10 disciplines and involving 8 research institutes and science departments). Activities have been concentrated on the implementation of the project's three primary functions: (1) coordination and management of the U of A ERTS-1 program, including management of the flow of data and data products; (2) acquisition, installation, test, operation, and maintanence of centralized facilities for processing ERTS-1, aircraft, and ground truth data; and (3) development of photographic and digital techniques for processing and interpreting ERTS-1 and aircraft data. With minor exceptions these three functions are now well-established and working smoothly.

  2. High-pressure amphibolite facies dynamic metamorphism and the Mesozoic tectonic evolution of an ancient continental margin, east- central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, C.; Hansen, V.L.; Scala, J.A.

    1995-01-01

    Ductilely deformed amphibolite facies tectonites comprise two adjacent terranes in east-central Alaska: the northern, structurally higher Taylor Mountain terrane and the southern, structurally lower Lake George subterrane of the Yukon-Tanana terrane. The pressure, temperature, kinematic and age data are interpreted to indicate that the metamorphism of the Taylor Mountain terrane and Lake George subterrane took place during different phases of a latest Palaeozoic through early Mesozoic shortening episode resulting from closure of an ocean basin now represented by klippen of the Seventymile-Slide Mountain terrane. High- to intermediate-pressure metamorphism of the Taylor Mountain terrane took place within a SW-dipping (present-day coordinates) subduction system. High- to intermediate-pressure metamorphism of the Lake George subterrane and the structural contact zone occurred during NW-directed overthrusting of the Taylor Mountain, Seventymile-Slide Mountain and Nisutlin terranes, and imbrication of the continental margin in Jurassic time. -from Authors

  3. A geochemical sampling technique for use in areas of active alpine glaciation: an application from the central Alaska Range

    USGS Publications Warehouse

    Stephens, G.C.; Evenson, E.B.; Detra, D.E.

    1990-01-01

    In mountainous regions containing extensive glacier systems there is a lack of suitable material for conventional geochemical sampling. As a result, in most geochemical sampling programs a few stream-sediment samples collected at, or near, the terminus of valley glaciers are used to evaluate the mineral potential of the glaciated area. We have developed and tested a technique which utilizes the medial moraines of valley glaciers for systematic geochemical exploration of the glacial catchment area. Moraine sampling provides geochemical information that is site-specific in that geochemical anomalies can be traced directly up-ice to bedrock sources. Traverses were made across the Trident and Susitna glaciers in the central Alaska Range where fine-grained (clay to sand size) samples were collected from each medial moraine. These samples were prepared and chemically analyzed to determine the concentration of specific elements. Fifty pebbles were collected at each moraine for archival purposes and for subsequent lithologic identification. Additionally, fifty cobbles and fifty boulders were examined and described at each sample site to determine the nature and abundance of lithologies present in the catchment area, the extent and nature of visible mineralization, the presence and intensity of hydrothermal alteration and the existence of veins, dikes and other minor structural features. Results from the central Alaska Range have delineated four distinct multi-element anomalies which are a response to potential mineralization up-ice from the medial moraine traverse. By integrating the lithologic, mineralogical and geochemical data the probable geological setting of the geochemical anomalies is determined. ?? 1990.

  4. 48 CFR 225.7704 - Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 3 2013-10-01 2013-10-01 false Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state in support of operations in... Operations in Afghanistan 225.7704 Acquisitions of products and services from South Caucasus/Central...

  5. 48 CFR 225.7704 - Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 3 2014-10-01 2014-10-01 false Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state in support of operations in... Operations in Afghanistan 225.7704 Acquisitions of products and services from South Caucasus/Central...

  6. Particulate Matter Concentration Levels in South Central Richmond, California (Invited)

    NASA Astrophysics Data System (ADS)

    Bonner, B.; Byias, C.; Cuff, K. E.; Diaz, J.; Love, K.; Marks-Block, T.; McLane, F.; Mollique, Z.; Montes, E.; Ross, R.; Washington, B.

    2009-12-01

    South Central Richmond, California is the home of one of the nation’s most innovative green workforce training centers, Richmond BUILD - Green Jobs Training facility. A near constant stream of young people engaged in training activities, instructors, invited guests, and journalists of various ages can be seen moving in and out of the facility nearly every day of the week throughout a given year. Additionally, the comings and goings of young children and adults associated with a mid-sized elementary school just north of the facility contributes to the general area’s substantial human traffic. Unfortunately, however, a major highway, Interstate 580, a major thoroughfare, 23rd Street and a railway line operated by Burlington Northern Santa Fe, Union Pacific, and the Richmond Pacific Railroad frame the triangular area within which these two sites are situated. In addition, a major petrochemical complex and several shipping facilities are located less than three kilometers away north and west of this area. As part of a general assessment of air quality in this heavily human traveled area, we conducted a study of particulate matter (PM) concentrations over a five-month period beginning in August of 2009. Measurements were made at a variety of locations, and results were used to map the spatial distribution of PM of various sizes. Regions of high concentration levels were identified, and these particular areas then were monitored over time. Preliminary results of our study indicate that regions with high concentrations are consistent across the range of particle sizes measured, which suggests a common source for PM found in the study area. As these regions are located close to a major thoroughfare and railway line, we believe that diesel-burning vehicles are major contributors to the PM levels found in the study area. Time series results suggest a fairly strong correlation between higher than average PM concentrations and abnormally high wind gusts. On days when wind

  7. 78 FR 16028 - Waiver of Restriction on Assistance to the Central Government of South Sudan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-13

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE Waiver of Restriction on Assistance to the Central Government of South Sudan Pursuant to Section 7031(b)(3... Section 7031(b)(1) of the Act with respect to South Sudan, and I hereby waive this restriction....

  8. Agrolandscape Research of Geosystems in the South of Central Siberia

    NASA Astrophysics Data System (ADS)

    Lysanova, G.; Soja, A. J.

    2012-12-01

    Minusinskaya basin, the area under research, is situated in the south of Central Siberia and is an agrarian region, which differs from another territories of Siberia. The territory provides for foodstuff not only its population but another regions as well. Nature-climate conditions favour the development of agriculture and cattle-breeding. Complex geographical study of rural lands, which is implemented by two approaches: a natural and industrial system block is necessary for rational use of agrolandscapes. Agrolandscapes are objects for rationalization of land management in agricultural regions. From our point of view application of a landscape map as a base for working out of agrolandscape map (Fig. 1a) and a map of agronatural potential of geosystems (Fig. 2), gives an opportunity to take stock of reserves of agricultural lands not only in quantitative but qualitative respects and also to determine the ways of optimal transformation of arable lands depending on nature conditions of regions and their development. Landscape maps that reflect differentiation of not only natural formations, changed by anthropogenious influence and also natural analogues, concern to a number of important tools of planning for optimal land use. The main principles of working out of typological landscape map of a medium scale aroused from targets and tasks of agrolandscape estimation of the territory [1]. The landscape map was worked out according to V.A. Nikolaev's methodology [2]: types of landscapes correlated with types of lands use, composition of cereals in rotation of crops, agro-techniques, crop capacity, climate indices, etc. Existing natural-agricultural systems are shown in the map. Their characteristics includes information about natural and agricultural blocks. Agronatural potential had been calculated by summarize estimations of its component parts. As a result of these calculations 30 arable agrolandscapes, marked out into the landscape map, were joined according to summ

  9. Variation in responses to spawning Pacific salmon among three south-eastern Alaska streams

    USGS Publications Warehouse

    Chaloner, D.T.; Lamberti, G.A.; Merritt, R.W.; Mitchell, N.L.; Ostrom, P.H.; Wipfli, M.S.

    2004-01-01

    1. Pacific salmon are thought to stimulate the productivity of the fresh waters in which they spawn by fertilising them with marine-derived nutrients (MDN). We compared the influence of salmon spawners on surface streamwater chemistry and benthic biota among three southeastern Alaska streams. Within each stream, reaches up- and downstream of barriers to salmon migration were sampled during or soon after spawners entered the streams. 2. Within streams, concentrations of dissolved ammonium and soluble reactive phosphorus (SRP), abundance of epilithon (chlorophyll a and ash-free dry mass) and biomass of chironomids were significantly higher in reaches with salmon spawners. In contrast, biomass of the mayflies Epeorus spp. and Rhithrogena spp. was significantly higher in reaches lacking spawners. 3. Among streams, significant differences were found in concentrations of dissolved ammonium, dissolved organic carbon, nitrate and SRP, abundance of epilithon, and the biomass of chironomids and Rhithrogena. These differences did not appear to reflect differences among streams in spawner density, nor the changes in water chemistry resulting from salmon spawners. 4. Our results suggest that the 'enrichment' effect of salmon spawners (e.g. increased streamwater nutrient concentrations) was balanced by other concurrent effects of spawners on streams (e.g. sediment disturbance). Furthermore, the collective effect of spawners on lotic ecosystems is likely to be constrained by conditions unique to individual streams, such as temperature, background water chemistry and light attenuation.

  10. Formation of lacustrine plains in west-central Alaska as a result of permafrost degradation and aggradation

    NASA Astrophysics Data System (ADS)

    Kanevskiy, M. Z.; Jorgenson, M. T.; Shur, Y.; O'Donnell, J.; Harden, J. W.; Fortier, D.

    2012-12-01

    Perennially frozen lacustrine sediments containing a large amount of ground ice comprise a significant part of the upper permafrost of the lowlands of west-central Alaska, including Koyukuk Flats and Innoko Flats. Study sites are located in the discontinuous permafrost zone, where permafrost was encountered mainly within uplifted peat plateaus. The upper part of studied sections is formed by frozen peat up to 3 m thick underlain by lacustrine silt, which is mostly ice-rich. Cryogenic structure of lacustrine sediments at different sites has common features: (1) prevalence of layered, braided, and reticulate cryostructures; (2) high variability in the ice content of sediments; (3) high density and low water content of soil aggregates separated by ice lenses. Volume of visible ice in silt reaches at places 40% and more. The thickness of ice lenses generally varies from 1 to 5 cm and occasionally reaches 10 cm. Remnants of peat plateaus are surrounded by unfrozen bogs and fens, formed as a result of thawing and settling of ice-rich lacustrine silt. Modern thermokarst scars initially form at places where ice-rich silt is not protected by a thick layer of organic material. Further development of thermokarst bogs includes lateral enlargement of thaw bulbs and collapsing of the margins of peat plateaus. Lacustrine silt within taliks is covered by woody peat accumulated under forests during the stage of permafrost plateau formation and then by aquatic sphagnum peat accumulated in taliks after collapse. We relate the formation of ice-rich lacustrine sediments to development of lake thermokarst, which affected ice-rich silty yedoma deposits during the transition from Pleistocene to Holocene. Terrain development in lacustrine lowlands of west-central Alaska includes five stages related to permafrost aggradation and degradation from the late Pleistocene to the present time: 1) formation of the ice-rich syngenetic permafrost (yedoma) during the late Pleistocene; 2) yedoma

  11. Glacimarine sedimentary processes, facies and morphology of the south-southeast Alaska shelf and fjords

    USGS Publications Warehouse

    Powell, R.D.; Molnia, B.F.

    1989-01-01

    High precipitation from Gulf of Alaska air masses can locally reach up to 800 cm a-1. This precipitation on tectonically active mountains creates cool-temperate glaciation with extremely active erosion and continuously renewed resources. High basal debris loads up to 1.5 m thick of pure debris and rapid glacial flow, which can be more than 3000 m a-1, combine to produce large volumes of siliciclastic glacimarine sediment at some of the highest sediment accumulation rates on record. At tidewater fronts of valley glaciers, sediment accumulation rates can be over 13 m a-1 and deltas commonly grow at about 106 m3 a-1. Major processes influencing glacimarine sedimentation are glacial transport and glacier-contact deposition, meltwater (subaerial and submarine) and runoff transport and deposition, iceberg rafting and gouging, sea-ice transport, wave action and storm reworking, tidal transport and deposition, alongshelf transport, sliding and slumping and gravity flows, eolian transport, and biogenic production and reworking. Processes are similar in both shelf and fjord settings; however, different intensities of some processes create different facies associations and geometries. The tectonoclimatic regime also controls morphology because bedrock structure is modified by glacial action. Major glacimarine depositional systems are all siliciclastic. They are subglacial, marginal-morainal bank and submarine outwash, and proglacial/paraglacial-fluvial/deltaic, beach, tidal flat/estuary, glacial fjord, marine outwash fjord and continental shelf. Future research should include study of long cores with extensive dating and more seismic surveys to evaluate areal and temporal extent of glacial facies and glaciation; time-series oceanographic data, sidescan sonar surveys and submersible dives to evaluate modern processes; biogenic diversity and production to evaluate paleoecological, paleobiogeographic and biofacies analysis; and detailed comparisons of exposed older rock of the

  12. Microbial enzyme activities of peatland soils in south central Alaska lowlands

    EPA Science Inventory

    Microbial enzyme activities related to carbon and nutrient acquisition were measured on Alaskan peatland soils as indicators of nutrient limitation and biochemical sustainability. Peat decomposition is mediated by microorganisms and enzymes that in turn are limited by various ph...

  13. Regional vertical tectonic displacement of shorelines in south- central Alaska during and between great earthquakes

    USGS Publications Warehouse

    Plafker, G.

    1990-01-01

    Reviews the setting of the 1964 earthquake and the unprecedented tectonic deformation that accompanied it. Outlines research directed towards defining the deformation that occurs between great earthquakes (interseismic part of the seismic cycle) and the longterm history of deformation over repeated seismic cycles in the earthquake-affected region, emphasizing work in progress. An understanding of this record of deformation is basic for evaluating how frequently 1964-type events recur in this same region, for improved understanding for the earthquake cycle in great subduction-zone seismotectonic events, and for predicting future great earthquakes in this and tectonically similar regions elsewhere. -from Author

  14. Late summer heat-transfer regimes at adjacent permafrost and non-permafrost sites in central Alaska

    SciTech Connect

    Hinkel, K.M.; Nicholas, J. . Dept. of Geography); Outcalt, S.I. . Dept. of Geological Sciences)

    1992-01-01

    Hourly observations of soil temperature and a surrogate index of soil water ion concentration were collected during late summer from the upper 50 cm of soil at two adjacent sites in the discontinuous permafrost zone of central Alaska. One site is above permafrost while the other, 13 m away in an area of weak groundwater discharge, has no underlying permafrost. At the permafrost site, temperatures at the surface of the dry, porous organic mat experienced large diurnal variation but temperature amplitude was strongly attenuated with depth. Steep thermal gradients induce diffusion of water vapor from the base of the active layer toward the surface. Evaporative cooling thus inhibits heat penetration and maintains subfreezing temperatures at depth. However, infiltration of precipitation is an effective method of transporting sensible heat to the base of the active layer and extending seasonal thaw depth above permafrost. Conversely, at the groundwater seep site, saturation maintained by throughflow damps temperature variation with time and depth, and precipitation has little impact on the evolution of the thermal regime. Soil conditions and precipitation patterns strongly influence the nonconductive heat flux component and produce complex spatial and temporal thaw patterns.

  15. Milankovitch insulation forcing and cyclic formation of large-scale glacial, fluvial, and eolian landforms in central Alaska

    NASA Technical Reports Server (NTRS)

    Beget, J. E.

    1993-01-01

    Continuous marine and ice-core proxy climate records indicate that the Earth's orbital geometry modulates long-term changes. Until recently, little direct evidence has been available to demonstrate correlations between Milankovitch cycles and large-scale terrestrial landforms produced during worldwide glaciations. In central Alaska large areas of loess and sand fill valleys and basins near major outwash streams. The streams themselves are bordered by sets of outwash terraces, and the terraces grade up valley into sets of moraines. The discovery of the Stampede tephra (approximately 175,000 yr ago) reworked within push moraines of the Lignite Creek glaciation suggests that this event correlates with the glaciation of marine isotope stage 6. A new occurrence of the Old Crow tephra (approximately 140,000 yr ago) on the surface of the oldest outwash terrace of the Tanana River, correlated with Delta glaciation, suggests this event also occurred at this time. The penultimate Healy glaciation apparently correlates with marine isotope stage 4, while radiocarbon dates indicate the latest Pleistocene moraines correlate with marine isotope stage 2. Recognition of the importance of orbital forcing to the cyclical formation of glacial landforms and landscapes can help in interpretations of remotely sensed glacial and proglacial land forms.

  16. Increased wetness confounds Landsat-derived NDVI trends in the central Alaska North Slope region, 1985–2011

    NASA Astrophysics Data System (ADS)

    Raynolds, Martha K.; Walker, Donald A.

    2016-08-01

    Satellite data from the circumpolar Arctic have shown increases in vegetation indices correlated to warming air temperatures (e.g. Bhatt et al 2013 Remote Sensing 5 4229–54). However, more information is needed at finer scales to relate the satellite trends to vegetation changes on the ground. We examined changes using Landsat TM and ETM+ data between 1985 and 2011 in the central Alaska North Slope region, where the vegetation and landscapes are relatively well-known and mapped. We calculated trends in the normalized difference vegetation index (NDVI) and tasseled-cap transformation indices, and related them to high-resolution aerial photographs, ground studies, and vegetation maps. Significant, mostly negative, changes in NDVI occurred in 7.3% of the area, with greater change in aquatic and barren types. Large reflectance changes due to erosion, deposition and lake drainage were evident. Oil industry-related changes such as construction of artificial islands, roads, and gravel pads were also easily identified. Regional trends showed decreases in NDVI for most vegetation types, but increases in tasseled-cap greenness (56% of study area, greatest for vegetation types with high shrub cover) and tasseled-cap wetness (11% of area), consistent with documented degradation of polygon ice wedges, indicating that increasing cover of water may be masking increases in vegetation when summarized using the water-sensitive NDVI.

  17. Geologic Model for Oil and Gas Assessment of the Kemik-Thomson Play, Central North Slope, Alaska

    USGS Publications Warehouse

    Schenk, Christopher J.; Houseknecht, David W.

    2008-01-01

    A geologic model was developed to assess undiscovered oil and gas resources in the Kemik-Thomson Play of the Central North Slope, Alaska. In this model, regional erosion during the Early Cretaceous produced an incised valley system on the flanks and crest of the Mikkelsen High and formed the Lower Cretaceous unconformity. Locally derived, coarse-grained siliciclastic and carbonate detritus from eroded Franklinian-age basement rocks, Carboniferous Kekiktuk Conglomerate (of the Endicott Group), Lisburne Group, and Permian-Triassic Sadlerochit Group may have accumulated in the incised valleys during lowstand and transgression, forming potential reservoirs in the Lower Cretaceous Kemik Sandstone and Thomson sandstone (informal term). Continued transgression resulted in the deposition of the mudstones of the over-lying Cretaceous pebble shale unit and Hue Shale, which form top seals to the potential reservoirs. Petroleum from thermally mature facies of the Triassic Shublik Formation, Jurassic Kingak Shale, Hue Shale (and pebble shale unit), and the Cretaceous-Tertiary Canning Formation might have charged Thomson and Kemik sandstone reservoirs in this play during the Tertiary. The success of this play depends largely upon the presence of reservoir-quality units in the Kemik Sandstone and Thomson sandstone.

  18. Milankovitch insulation forcing and cyclic formation of large-scale glacial, fluvial, and eolian landforms in central Alaska

    NASA Astrophysics Data System (ADS)

    Beget, J. E.

    Continuous marine and ice-core proxy climate records indicate that the Earth's orbital geometry modulates long-term changes. Until recently, little direct evidence has been available to demonstrate correlations between Milankovitch cycles and large-scale terrestrial landforms produced during worldwide glaciations. In central Alaska large areas of loess and sand fill valleys and basins near major outwash streams. The streams themselves are bordered by sets of outwash terraces, and the terraces grade up valley into sets of moraines. The discovery of the Stampede tephra (approximately 175,000 yr ago) reworked within push moraines of the Lignite Creek glaciation suggests that this event correlates with the glaciation of marine isotope stage 6. A new occurrence of the Old Crow tephra (approximately 140,000 yr ago) on the surface of the oldest outwash terrace of the Tanana River, correlated with Delta glaciation, suggests this event also occurred at this time. The penultimate Healy glaciation apparently correlates with marine isotope stage 4, while radiocarbon dates indicate the latest Pleistocene moraines correlate with marine isotope stage 2. Recognition of the importance of orbital forcing to the cyclical formation of glacial landforms and landscapes can help in interpretations of remotely sensed glacial and proglacial land forms.

  19. 48 CFR 225.7704 - Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 3 2011-10-01 2011-10-01 false Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state in support of operations in... Operations in Iraq or Afghanistan 225.7704 Acquisitions of products and services from South...

  20. 48 CFR 225.7704 - Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 3 2012-10-01 2012-10-01 false Acquisitions of products and services from South Caucasus/Central and South Asian (SC/CASA) state in support of operations in... Operations in Iraq or Afghanistan 225.7704 Acquisitions of products and services from South...

  1. Physical characteristics of stream subbasins in the Blue Earth River Basin, south-central Minnesota and north-central Iowa

    USGS Publications Warehouse

    Lorenz, D.L.; Payne, G.A.

    1992-01-01

    This report presents data describing the physical characteristics of stream basins upstream from selected points on streams in the Blue Earth River basin, located in south-central Minnesota and north-central Iowa. The physical characteristics are the drainage area of the basin, the percentage area of the basin covered only by lakes, the percentage area of the basin covered by both lakes and wetlands, the main-channel length, and the mainchannel slope. The points on the stream include outlets of subbasins of at least five square miles, outfalls of sewage treatment plants, and locations of U.S. Geological Survey gaging stations.

  2. A 2000 year varve-based climate record from the central Brooks Range, Alaska

    SciTech Connect

    Bird, BW; Abbott, MB; Finney, BP; Kutchko, B

    2009-01-01

    Varved minerogenic sediments from glacial-fed Blue Lake, northern Alaska, are used to investigate late Holocene climate variability. Varve-thickness measurements track summer temperature recorded at Atigun Pass, located 41 km east at a similar elevation (r (2) = 0.31, P = 0.08). Results indicate that climate in the Brooks Range from 10 to 730 AD (varve year) was warm with precipitation inferred to be higher than during the twentieth century. The varvetemperature relationship for this period was likely compromised and not used in our temperature reconstruction because the glacier was greatly reduced, or absent, exposing sub-glacial sediments to erosion from enhanced precipitation. Varve-inferred summer temperatures and precipitation decreased after 730 AD, averaging 0.4A degrees C above the last millennial average (LMA = 4.2A degrees C) from 730 to 850 AD, and 0.1A degrees C above the LMA from 850 to 980 AD. Cooling culminated between 980 and 1030 AD with temperatures 0.7A degrees C below the LMA. Varve-inferred summer temperatures increased between 1030 and 1620 AD to the LMA, though the period between 1260 and 1350 AD was 0.2A degrees C below the LMA. Although there is no equivalent to the European Medieval Warm Period in the Blue Lake record, two warm intervals occurred from 1350 to 1450 AD and 1500 to 1620 AD (0.4 and 0.3A degrees C above the LMA, respectively). During the Little Ice Age (LIA; 1620 to 1880 AD), inferred summer temperature averaged 0.2A degrees C below the LMA. After 1880 AD, inferred summer temperature increased to 0.8A degrees C above the LMA, glaciers retreated, but aridity persisted based on a number of regional paleoclimate records. Despite warming and glacial retreat, varve thicknesses have not achieved pre-730 AD levels. This reflects limited sediment availability and transport due to a less extensive retreat compared to the first millennium, and continued relative aridity. Overall, the Blue Lake record is similar to varve records from the

  3. Preliminary geology of eastern Umtanum Ridge, South-Central Washington

    SciTech Connect

    Goff, F.E.

    1981-01-01

    The basalt stratigraphy and geologic structures of eastern Umtanum Ridge have been mapped and studied in detail to help assess the feasibility of nuclear waste terminal storage on the Hanford Site in southeastern Washington State. Eastern Umtanum Ridge is an asymmetric east-west-trending anticline of Columbia River basalt that plunges 5 degrees eastward into the Pasco Basin. Geologic mapping and determination of natural remanent magnetic polarity and chemical composition reveal that flows of the Pomona and Umatilla Members (Saddle Mountains Basalt), Priest Rapids and Frenchman Springs Members (Wanapum Basalt), and Grande Ronde Basalt were erupted as fairly uniform sheets. The Wahluke and Huntzinger flows (Saddle Mountains Basalt) fill a paleovalley cut into Wanapum Basalt. No evidence was found to indicate Quaternary-age movement on any structures in the map area. The basalt strata on the south limb of the Umtanum anticline display relatively little tectonic deformation since Miocene-Pliocene time. Thus, the buried south flank of Umtanum Ridge may provide an excellent location for a nuclear waste repository beneath the Hanford Site.

  4. Late Mesozoic and Cenozoic thermotectonic evolution of the central Brooks Range and adjacent North Slope foreland basin, Alaska: Including fission track results from the Trans-Alaska Crustal Transect (TACT)

    USGS Publications Warehouse

    O'Sullivan, P. B.; Murphy, J.M.; Blythe, A.E.

    1997-01-01

    Apatite fission track data are used to evaluate the thermal and tectonic history of the central Brooks Range and the North Slope foreland basin in northern Alaska along the northern leg of the Trans-Alaska Crustal Transect (TACT). Fission track analyses of the detrital apatite grains in most sedimentary units resolve the timing of structures and denudation within the Brooks Range, ranging in scale from the entire mountain range to relatively small-scale folds and faults. Interpretation of the results indicates that rocks exposed within the central Brooks Range cooled rapidly from paleotemperatures 110?? to 50??C during discrete episodes at ???100??5 Ma, ???60??4 Ma, and ???24??3 Ma, probably in response to kilometer-scale denudation. North of the mountain front, rocks in the southern half of the foreland basin were exposed to maximum paleotemperatures 110??C in the Late Cretaceous to early Paleocene as a result of burial by Upper Jurassic and Cretaceous sedimentary rocks. Rapid cooling from these elevated paleotemperatures also occurred due to distinct episodes of kilometer-scale denudation at ???60??4 Ma, 46??3 Ma, 35??2 Ma, and ???24??3 Ma. Combined, the apatite analyses indicate that rocks exposed along the TACT line through the central Brooks Range and foreland basin experienced episodic rapid cooling throughout the Late Cretaceous and Cenozoic in response to at least three distinct kilometer-scale denudation events. Future models explaining orogenic events in northern Alaska must consider these new constraints from fission track thermochronology. Copyright 1997 by the American Geophysical Union.

  5. Multistory duplexes with forward dipping roofs, north central Brooks Range, Alaska

    USGS Publications Warehouse

    Wallace, W.K.; Moore, T.E.; Plafker, G.

    1997-01-01

    The Endicott Mountains allochthon has been thrust far northward over the North Slope parautochthon in the northern Brooks Range. Progressively younger units are exposed northward within the allochthon. To the south, the incompetent Hunt Fork Shale has thickened internally by asymmetric folds and thrust faults. Northward, the competent Kanayut Conglomerate forms a duplex between a floor thrust in Hunt Fork and a roof thrust in the Kayak Shale. To the north, the competent Lisburne Group forms a duplex between a floor thrust in Kayak and a roof thrust in the Siksikpuk Formation. Both duplexes formed from north vergent detachment folds whose steep limbs were later truncated by south dipping thrust faults that only locally breach immediately overlying roof thrusts. Within the parautochthon, the Kayak, Lisburne, and Siksikpuk-equivalent Echooka Formation form a duplex identical to that in the allochthon. This duplex is succeeded abruptly northward by detachment folds in Lisburne. These folds are parasitic to an anticlinorium interpreted to reflect a fault-bend folded horse in North Slope "basement," with a roof thrust in Kayak and a floor thrust at depth. These structures constitute two northward tapered, internally deformed wedges that are juxtaposed at the base of the allochthon. Within each wedge, competent units have been shortened independently between detachments, located mainly in incompetent units. The basal detachment of each wedge cuts upsection forward (northward) to define a wedge geometry within which units dip regionally forward. These dips reflect forward decrease in internal structural thickening by forward vergent folds and hindward dipping thrust faults. Copyright 1997 by the American Geophysical Union.

  6. 1994 Volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    Neal, Christina A.; Doukas, Michael P.; McGimsey, Robert G.

    1995-01-01

    During 1994, the Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, or false alarms at nine volcanic centers-- Mount Sanford, Iliamna, the Katmai group, Kupreanof, Mount Veniaminof, Shishaldin, Makushin, Mount Cleveland and Kanaga (table 1). Of these volcanoes, AVO has a real time, continuously recording seismic network only at Iliamna, which is located in the Cook Inlet area of south-central Alaska (fig. 1). AVO has dial-up access to seismic data from a 5-station network in the general region of the Katmai group of volcanoes. The remaining unmonitored volcanoes are located in sparsely populated areas of the Wrangell Mountains, the Alaska Peninsula, and the Aleutian Islands (fig. 1). For these volcanoes, the AVO monitoring program relies chiefly on receipt of pilot reports, observations of local residents and analysis of satellite imagery.

  7. Late Cretaceous Middle Fork caldera and its resurgent granite porphyry intrusion, east-central Alaska

    NASA Astrophysics Data System (ADS)

    Bacon, C. R.; Dusel-Bacon, C.; Aleinikoff, J. N.; Slack, J. F.

    2012-12-01

    to have been exposed by erosion of thick intracaldera tuff from an asymmetric resurgent dome. The Middle Fork of the North Fork of the Fortymile River cuts an arcuate valley into and around the caldera on the west and north, and may have cut down from an original caldera moat. Proximal outflow tuff, and thus the 69 Ma land surface, remains at the west margin of the caldera structure. The Middle Fork caldera lies within a region of Paleozoic metamorphic rocks and Mesozoic plutons bounded by northeast-trending faults. To the northwest, Cretaceous plutonic rocks are widely exposed, indicating greater exhumation. The Middle Fork is a relatively well preserved caldera within a broad region of Alaska and adjacent Yukon that contains Late Cretaceous plutons and, in the less deeply exhumed blocks, silicic volcanic rocks.

  8. Bibliography for Hayes, Spurr, Crater Peak, Redoubt, Iliamna, Augustine, Douglas, and Aniakchak volcanoes, Alaska

    USGS Publications Warehouse

    Lemke, K.J.; May, B.A.; Vanderpool, A.M.

    1995-01-01

    Alaska has more than 40 active volcanoes, many of which are close to the major population centers of south-central Alaska. This bibliography was compiled to assist in the preparation of volcano hazard evaluations at Cook Inlet volcanoes. It lists articles, reports, and maps about the geology and hydrology of Hayes, Spurr, Redoubt, Iliamna, Augustine, and Douglas volcanoes in the Cook Inlet region as well as Aniakchak Volcano on the Alaska Peninsula. References on the biology and archaeology of areas surrounding each volcano also are included because they may provide useful background information.

  9. Late Cenozoic structure and stratigraphy of south-central Washington

    SciTech Connect

    Reidel, S.P. |; Campbell, N.P.; Fecht, K.R.; Lindsey, K.A.

    1993-09-01

    The structural framework of the Columbia Basin began developing before Columbia River Basalt Group (CRBG) volcanism. Prior to 17.5 Ma, the eastern part of the basin was a relatively stable area, with a basement of Paleozoic and older crystalline rock. The western part was an area of subsidence in which large volumes of sediment and volcanic rocks accumulated. Concurrent with eruption of the CRBG, anticlinal ridges of the Yakima Fold Belt (YFB) were growing under north-south compression. Topographic expression of these features was later masked by the large volume of CRBG basalt flowing west from fissures in the eastern Columbia Basin. The folds continued to develop after cessation of volcanism, leading to as much as 1,000 m of structural relief in the past 10 million years. Post-CRBG evolution of the Columbia Basin is recorded principally in folding and faulting in the YFB and sediments deposited in the basins. The accompanying tectonism resulted in lateral migration of major depositional systems into subsiding structural lows. Although known late Cenozoic faults are on anticlinal ridges, earthquake focal mechanisms and contemporary strain measurements indicate most stress release is occurring in the synclinal areas under north-south compression. There is no obvious correlation between focal mechanisms for earthquakes whose foci are in the CRBG and the location of known faults. High in situ stress values help to explain the occurrence of microseismicity in the Columbia Basin but not the pattern. Microseismicity appears to occur in unaltered fresh basalt. Faulted basalt associated with the YFB is highly brecciated and commonly altered to clay. The high stress, abundance of ground water in confined aquifers of the CRBG, and altered basalt in fault zones suggest that the frontal faults on the anticlinal ridges probably have some aseismic deformation. 85 refs.

  10. Use of Radarsat-2 Polarimetric SAR Images for Fuel Moisture Mapping in Alaska Boreal Forests and South Africa Savannahs

    NASA Astrophysics Data System (ADS)

    Leblon, B.; Bourgeau-Chavez, L. L.; Kong, M.; Buckley, J. R.; Mathieu, R. M.; Charbonneau, F.; Gross, C. P.; Naidoo, L.

    2014-12-01

    The study reported a comparison between two Radarsat-2 polarimetric SAR (polSAR) images from extreme dry versus wet conditions are compared in an effort to determine the value of using polarimetric SAR data for estimating fuel moisture over South Africa savannahs and Alaska boreal forests. The savannahs study area is located into the Kruger National Park area and has 36 sites of lowveld savannas from bare overgrazed sites to medium-dense savannahs. The boreal forest study area has a chronosequence of black spruce ecosystems (recent burns, shrub-dominated regenerating forests , open canopied forests, moderately dense forest cover). Both study areas have a fairly level topography suitable for radar studies. The polSAR images were acquired using the same beam mode (FQ5 (23-25° incidence angle over the boreal sites, FQ15 (34.47-36.05° incidence angle) over the savannahs sites). Over each study area, soil moisture and vegetation structural data were measured in situ concurrently to the acquisition of the SAR imagery. The polSAR images were filtered for speckle noise using a Lee sigma filter and several polarimetric products were computed, such as those directly derived from the images (single linear and polairzed backscatters, polarimetric discriminators) and from target decompositions (Freeman-Durden, new van Zyl, Cloude-Pottier). Because most of these variables have a different unit, a normalized difference (in %) for each variable was calculated using the median values of the dry and wet dates for easier comparison of variable changes between the dates. Over both study areas, the normalized difference between wet and dry conditions was lower when higher tree canopy occurs. Results show utility of C-HH and C-RR polarized backscatters. Several polarimetric discriminators (dmin, Pr max, Pr min, Smax, Smin) were also significantly affected by the soil wetness. The Freeman Durden and van Zyl decomposition parameters outperformed the Cloude-Pottier decomposition

  11. Lisburne Group (Mississippian-Lower Permian) petrography, paragenesis, and hydrocarbon potential, central Brooks Range, Alaska

    SciTech Connect

    Krutak, P.R.

    1989-03-01

    Subsurface Lisburne Group (Wahoo) rocks at Prudhoe Bay-Kuparuk fields produce 2 million bbl of oil/day and contain 2-3 billion bbl of oil in place. Lisburne reservoirs are early diagenetic dolomites encased in thick platform carbonates. Petrographic and geochemical study of 264 samples from eight newly discovered surface Lisburne sections comprising 4568 ft of strata in the Central Brooks Range provide new data concerning paragenesis and hydrocarbon potential of Lisburne facies farther west. A generalized paragenetic sequence for Lisburne equivalents of this region is (1) initial carbonate skeletal growth (both aragonite and calcite) during the Carboniferous, (2) subsequent recrystallization and inversion of aragonite to calcite, the change to calcite proceeding throughout late Paleozoic and Permian-Triassic time, (3) dolomitization in the Middle and Late Carboniferous, (4) chertification and silicification, postdating slightly or overlapping dolomitization, (5) development of porosity (moldic, intracrystal, etc.) in the middle to late Mesozoic, (6) formation of fracture porosity concurrent with the Brooks Range orogeny during Middle Jurassic-Cretaceous time, (7) oil generation, migration, and emplacement in Late Cretaceous-Tertiary time. Lisburne dolomites from the Central Brooks Range bear heavy hydrocarbons. Rock-Eval pyrolysis indicates part of the section is in the oil window and near the peak wet-gas generation zone. Shale samples from this region display thermal alteration indices and vitrinite reflectance values near the oil floor and also indicate potential for sourcing dry gas. Conodont color alteration indices show part of the Lisburn could produce dry gas.

  12. Effects of drought in central and south Texas

    USGS Publications Warehouse

    Thomas, H.E.; Others

    1963-01-01

    The effects of drought upon ground-water storage and discharge, and upon streamflow, vary tremendously in the central third of Texas (the area from the Panhandle to the Gulf of Mexico). Extremes are represented by (a) the Llano Estacado, where the drought had negligible effect upon ground-water resources, which are being progressively depleted by pumping for irrigation; and (b) the Balcones fault-zone aquifer west of San Antonio, whose storage and natural discharge declined substantially during the drought, but increased even more rapidly during succeeding years of more abundant precipitation.

  13. The Last Termination in the Central South Atlantic

    NASA Astrophysics Data System (ADS)

    Sjolte, J.; Ljung, K.; Holmgren, S.; Kylander, M. E.; Van der Putten, N.; Kageyama, M.; Porter, C. T., Jr.; Bjorck, S.

    2015-12-01

    We present results from analysis of lake sediments and peat deposits from two basins on Nightingale Island (37°S), in the Tristan da Cunha archipelago, South Atlantic. The studies were focused on the time period 16.2-10.0 cal ka BP. A wide variety of proxies were used, including pollen and diatom analyzes, biogenic silica content, bulk C and N content, stable isotopes (13C and 15N), elemental concentrations and magnetic susceptibility measurements, to detect environmental changes that can be related to shifts of the circulation belts of the Southern Ocean. We find that the sediments are underlain by a >2 cal ka BP long hiatus, possibly representing a dried-out lake bed. Climate simulations corroborate that the area might have been exposed to arid conditions as a consequence of the Heinrich 1 event in the north and a southward displacement of the ITCZ. We interpret the results as being related to the position of the Subtropical Front (STF) and the Southern Hemisphere Westerlies (SHW). During 16.2-14.75 cal ka BP the SHW and STF were situated south of Tristan da Cunha. The data indicates moderate variability ending with a humidity peak and cooler conditions. The conditions during 14.7-14.1 cal ka BP were more stable with cool and arid conditions implying that the STF and SHW were both north of the islands during the first part of the Antarctic Cold Reversal. The period 14.1-12.7 cal ka BP indicates incessant latitudinal shifts of the zonal circulation, perhaps related the bipolar seesaw mechanisms. At 12.7 cal ka BP the Holocene warming began with a gradually drier and warmer climate as a result of a dampened AMOC during the Younger Dryas cooling in the north with ITCZ, STF and SHW being displaced southwards. Peak warming seems to have occurred in the earliest part of the Holocene, but this period was also characterized by humidity shifts, possibly an effect of retraction and expansion phases of SHW during AMOC variations in the north.

  14. The last termination in the central South Atlantic

    NASA Astrophysics Data System (ADS)

    Ljung, Karl; Holmgren, Sofia; Kylander, Malin; Sjolte, Jesper; Van der Putten, Nathalie; Kageyama, Masa; Porter, Charles T.; Björck, Svante

    2015-09-01

    Lake sediments and peat deposits from two basins on Nightingale Island (37°S), in the Tristan da Cunha archipelago, South Atlantic, have been analyzed. The studies were focused on the time period 16.2-10.0 cal ka BP, determined by 36 14C dates from the two sequences. A wide variety of proxies were used, including pollen and diatom analyzes, biogenic silica content, C and N analyzes, stable isotopes (13C and 15N), elemental concentrations and magnetic susceptibility measurements, to detect environmental changes that can be related to shifts of the circulation belts of the Southern Ocean. In addition, climate model simulations were carried out. We find that the sediments are underlain by a >2 cal ka BP long hiatus, possibly representing a dried-out lake bed. The climate simulations corroborate that the area might have been exposed to arid conditions as a consequence of the Heinrich 1 event in the north and a southward displacement of the ITCZ. The development on the island after 16.2 cal ka BP is determined by the position of the Subtropical Front (STF) and the Southern Hemisphere Westerlies (SHW). The period 16.2-14.75 cal ka BP was characterized by varying influence from SHW and with STF situated south of Tristan da Cunha, ending with a humidity peak and cooler conditions. The stable conditions 14.7-14.1 cal ka BP with cool and fairly arid conditions imply that STF and SHW were both north of the islands during the first part of the Antarctic Cold Reversal. The most unstable period, 14.1-12.7 cal ka BP, indicates incessant latitudinal shifts of the zonal circulation, perhaps related to climate variability in the Northern Hemisphere and bipolar seesaw mechanisms as the strength of the Atlantic Meridional Overturning Circulation (AMOC) varied. At 12.7 cal ka BP the Holocene warming began with a gradually drier and warmer climate as a result of a dampened AMOC during the Younger Dryas cooling in the north with ITCZ, STF and SHW being displaced southwards. Peak warming

  15. Detection of east/central/south African genotype of chikungunya virus in Myanmar, 2010.

    PubMed

    Tun, Mya Myat Ngwe; Thant, Kyaw Zin; Inoue, Shingo; Nabeshima, Takeshi; Aoki, Kotaro; Kyaw, Aung Kyaw; Myint, Tin; Tar, Thi; Maung, Kay Thwe Thwe; Hayasaka, Daisuke; Morita, Kouichi

    2014-08-01

    In 2010, chikungunya virus of the East Central South African genotype was isolated from 4 children in Myanmyar who had dengue-like symptoms. Phylogenetic analysis of the E1 gene revealed that the isolates were closely related to isolates from China, Thailand, and Malaysia that harbor the A226V mutation in this gene. PMID:25062511

  16. Looking south through east portion of Centralized Work Equipment (C.W.E.) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Looking south through east portion of Centralized Work Equipment (C.W.E.) Storage Shed (Bldg. 126). Note overhead monorails for material-handling hoists. This shed stored track maintenance materials - Atchison, Topeka, Santa Fe Railroad, Albuquerque Shops, C.W.E. Storage Shed, 908 Second Street, Southwest, Albuquerque, Bernalillo County, NM

  17. Detection of East/Central/South African Genotype of Chikungunya Virus in Myanmar, 2010

    PubMed Central

    Tun, Mya Myat Ngwe; Thant, Kyaw Zin; Inoue, Shingo; Nabeshima, Takeshi; Aoki, Kotaro; Kyaw, Aung Kyaw; Myint, Tin; Tar, Thi; Maung, Kay Thwe Thwe; Hayasaka, Daisuke

    2014-01-01

    In 2010, chikungunya virus of the East Central South African genotype was isolated from 4 children in Myanmyar who had dengue-like symptoms. Phylogenetic analysis of the E1 gene revealed that the isolates were closely related to isolates from China, Thailand, and Malaysia that harbor the A226V mutation in this gene. PMID:25062511

  18. U.S. Blacks' Perceptions, Experiences, and Scholarship regarding Central and South America--1822 to 1959

    ERIC Educational Resources Information Center

    Fikes, Robert, Jr.

    2006-01-01

    Instances of U.S. Black Americans having direct contact with the inhabitants of Central and South America, whose majority populations are not Black, can be traced back to the early nineteenth century. Slaves and freemen were aware of the possibility of a better life in these regions and a few found their way there to experience trials,…

  19. 40 CFR 81.166 - South Central Coast Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 18 2012-07-01 2012-07-01 false South Central Coast Intrastate Air Quality Control Region. 81.166 Section 81.166 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES Designation of Air Quality Control Regions § 81.166...

  20. 40 CFR 81.166 - South Central Coast Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 18 2014-07-01 2014-07-01 false South Central Coast Intrastate Air Quality Control Region. 81.166 Section 81.166 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES Designation of Air Quality Control Regions § 81.166...

  1. 40 CFR 81.105 - South Central Pennsylvania Intrastate Air Quality Control Region.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DESIGNATION OF AREAS FOR AIR QUALITY PLANNING PURPOSES... Region. The South Central Pennsylvania Intrastate Air Quality Control Region consists of the territorial... territorial area of all municipalities (as defined in section 302(f) of the Clean Air Act, 42 U.S.C....

  2. Atrazine in Source Water Intended for Artificial Ground-Water Recharge, South-Central Kansas

    USGS Publications Warehouse

    Christensen, Victoria G.; Ziegler, Andrew C.

    1998-01-01

    Atrazine, an herbicide commonly applied to row crops, is of concern because of potential effects on water quality. This fact sheet describes atrazine in water from the Little Arkansas River in south-central Kansas. The river is being evaluated as a source of artificial recharge into the Equus Beds aquifer, which provides water for the city of Wichita.

  3. Steelhead of the south-central/southern California coast: Population characterization for recovery planning

    USGS Publications Warehouse

    Boughton, David A.; Adams, P.B.; Anderson, E.; Fusaro, Craig; Keller, E.; Kelley, Elsie; Lentsch, Leo; Nielsen, J. L.; Perry, Katie; Regan, Helen; Swift, C.; Watson, Fred

    2006-01-01

    This report by the National Marine Fisheries Service applies a formal evaluation framework to the problem of delineating Oncorhynchus mykiss populations in the South-Central/Southern California Coast recovery domain, in support of recovery planning under the Endangered Species Act.

  4. Imaging the transition from Aleutian subduction to Yakutat collision in central Alaska, with local earthquakes and active source data

    USGS Publications Warehouse

    Eberhart-Phillips, D.; Christensen, D.H.; Brocher, T.M.; Hansen, R.; Ruppert, N.A.; Haeussler, P.J.; Abers, G.A.

    2006-01-01

    In southern and central Alaska the subduction and active volcanism of the Aleutian subduction zone give way to a broad plate boundary zone with mountain building and strike-slip faulting, where the Yakutat terrane joins the subducting Pacific plate. The interplay of these tectonic elements can be best understood by considering the entire region in three dimensions. We image three-dimensional seismic velocity using abundant local earthquakes, supplemented by active source data. Crustal low-velocity correlates with basins. The Denali fault zone is a dominant feature with a change in crustal thickness across the fault. A relatively high-velocity subducted slab and a low-velocity mantle wedge are observed, and high Vp/Vs beneath the active volcanic systems, which indicates focusing of partial melt. North of Cook Inlet, the subducted Yakutat slab is characterized by a thick low-velocity, high-Vp/Vs, crust. High-velocity material above the Yakutat slab may represent a residual older slab, which inhibits vertical flow of Yakutat subduction fluids. Alternate lateral flow allows Yakutat subduction fluids to contribute to Cook Inlet volcanism and the Wrangell volcanic field. The apparent northeast edge of the subducted Yakutat slab is southwest of the Wrangell volcanics, which have adakitic composition consistent with melting of this Yakutat slab edge. In the mantle, the Yakutat slab is subducting with the Pacific plate, while at shallower depths the Yakutat slab overthrusts the shallow Pacific plate along the Transition fault. This region of crustal doubling within the shallow slab is associated with extremely strong plate coupling and the primary asperity of the Mw 9.2 great 1964 earthquake. Copyright 2006 by the American Geophysical Union.

  5. Three-dimensional model of an ultramafic feeder system to the Nikolai Greenstone mafic large igneous province, central Alaska Range

    USGS Publications Warehouse

    Glen, J.M.G.; Schmidt, J.M.; Connard, G.G.

    2011-01-01

    The Amphitheater Mountains and southern central Alaska Range expose a thick sequence of Triassic Nikolai basalts that is underlain by several mafic-ultramafic complexes, the largest and best exposed being the Fish Lake and Tangle (FL-T) mafic-ultramafic sills that flank the Amphitheater Mountains synform. Three-dimensional (3-D) modeling of gravity and magnetic data reveals details of the structure of the Amphitheater Mountains, such as the orientation and thickness of Nikolai basalts, and the geometry of the FL-T intrusions. The 3-D model (50 ?? 70 km) includes the full geographic extent of the FL-T complexes and consists of 11 layers. Layer surfaces and properties (density and magnetic susceptibility) were modified by forward and inverse methods to reduce differences between the observed and calculated gravity and magnetic grids. The model suggests that the outcropping FL-T sills are apparently connected and traceable at depth and reveals variations in thickness, shape, and orientation of the ultramafic bodies that may identify paths of magma flow. The model shows that a significant volume (2000 km3) of ultramafic material occurs in the subsurface, gradually thickening and plunging westward to depths exceeding 4 km. This deep ultramafic material is interpreted as the top of a keel or root system that supplied magma to the Nikolai lavas and controlled emplacement of related magmatic intrusions. The presence of this deep, keel-like structure, and asymmetry of the synform, supports a sag basin model for development of the Amphitheater Mountains structure and reveals that the feeders to the Nikolai are much more extensive than previously known. Copyright 2011 by the American Geophysical Union.

  6. Detrital zircon geochronology of the Adams Argillite and Nation River Formation, east-central Alaska, U.S.A

    USGS Publications Warehouse

    Gehrels, G.E.; Johnsson, M.J.; Howell, D.G.

    1999-01-01

    The Cambrian Adams Argillite and the Devonian Nation River Formation are two sandstone-bearing units within a remarkably complete Paleozoic stratigraphic section in east-central Alaska. These strata, now foreshortened and fault-bounded, were originally contiguous with miogeoclinal strata to the east that formed as a passive-margin sequence along the northwestern margin of the North American continent. Seventy-five detrital zircon grains from the Adams Argillite and the Nation River Formation were analyzed in an effort to provide constraints on the original sources of the grains, and to generate a detrital zircon reference for miogeoclinal strata in the northern Cordillera. Thirty-five single zircon grains from a quartzite in the Adams Argillite yield dominant age clusters of 1047-1094 (n = 6), 1801-1868 (n = 10), and 2564-2687 (n = 5) Ma. Forty zircons extracted from a sandstone in the Nation River Formation yield clusters primarily of 424-434 (n = 6), 1815-1838 (n = 6), 1874-1921 (n = 7), and 2653-2771 (n = 4) Ma. The Early Proterozoic and Archean grains in both units probably originated in basement rocks in a broad region of the Canadian Shield. In contrast, the original igneous sources for mid-Protcrozoic grains in the Adams Argillite and ??? 430 Ma grains in the Nation River Formation are more difficult to identify. Possible original sources for the mid-Proterozoic grains include: (1) the Grenville Province of eastern Laurentia, (2) the Pearya terrane along the Arctic margin, and (3) mid-Proterozoic igneous rocks that may have been widespread along or outboard of the Cordilleran margin. The ??? 430 Ma grains may have originated in: (1) arc-type sources along the Cordilleran margin, (2) the Caledonian orogen, or (3) a landmass, such as Pearya, Siberia, or crustal fragments now in northern Asia, that resided outboard of the Innuitian orogen during mid-Paleozoic time. Copyright ?? 1999, SEPM (Society for Sedimentary Geology).

  7. Spiculitic chert reservoir in Glick Field, South-Central Kansas

    SciTech Connect

    Rogers, J.P.; Longman, M.W.; Lloyd, R.M.

    1995-01-01

    Glick Field, located in Kiowa and Comanche counties of southern Kansas, was discovered in 1957 and has produced more than 362 BCF from Mississippian Osage chert, commonly referred to as the {open_quotes}Chat.{close_quotes} Other {open_quotes}CHAT{close_quotes} reservoirs in Kansas and Oklahoma produce mainly from mixed chert and dolomite beneath the pre-Pennsylvanian unconformity, but Glick Field`s reservoir is dominated by chert containing abundant sponge spicules. Glick Field is a stratigraphic trap with production ending where the spiculitic facies pinches out into tight limestones to the south and west which provide a lateral seal. Additionally, updip, to the northeast, the productive facies is truncated by the unconformity. Reworked chert conglomerates overlying the spiculitic reservoir at the unconformity also produce some gas. The spiculitic chert forming the reservoir was desposited below storm wavebase and grades laterally in all directions into echinoderm and brachiopod-rich skeletal wackestones and lime mudstones. Even where completely silicified, these associated limestone are tight. Thus, the reservoir is an in situ oval-shaped complex of internally brecciated sponge mats and bioherms capped in part by the chert conglomerate. The spiculitic chert contains up to 50% porosity in molds after sponge spicules, matrix micropores and vugs are connected in part by fracture and breccia porosity. Distribution of the sponge bioherms which form the reservoir facies was partly controlled by a subtle change on the shallow Mississippian carbonate shelf from clean skeletal limestones southward into shaly (and probably more anoxic) carbonates known locally as the {open_quotes}Cowley Facies.{close_quotes} The sponge bioherms formed most commonly just updip from this boundary, which can be mapped across southern Kansas. Thus, lithologic mapping provides a potential exploration tool with which to find other stratigraphically trapped spiculitic reservoirs in the area.

  8. Lateral continuity of the Blarney Creek Thrust, Doonerak Windown, Central Brooks Range, Alaska

    SciTech Connect

    Seidensticker, C.M.; Julian, F.E.; Phelps, J.C.; Oldow, J.S.; Avellemant, H.G.

    1985-04-01

    The contact between Carboniferous and lower Paleozoic rocks, exposed along the northern margin of the Doonerak window in the central Brooks Range, is a major thrust fault called the Blarney Creek thrust (BCT). The BCT has been traced over a distance of 25 km, from Falsoola Mountain to Wien Mountain. The tectonic nature of this contact is demonstrated by: (1) omission of stratigraphic units above and below the BCT; (2) large angular discordance in orientation of first-generation cleavage at the BCT; (3) numerous thrust imbricates developed in the upper-plate Carboniferous section that sole into the BCT; and (4) truncation of an upper-plate graben structure at the BCT. Lack of evidence for pre-Carboniferous deformation in the lower plate casts doubt on the interpretation of the contact as an angular unconformity. However, the localized presence below the BCT of Mississippian Kekiktuk Conglomerate and Kayak Shale, in apparent depositional contact with lower Paleozoic rocks, suggests that the BCT follows an originally disconformable contact between the Carboniferous and lower Paleozoic rocks. The juxtaposition of younger over older rocks at the BCT is explained by calling upon the BCT to act as the upper detachment surface of a duplex structure. Duplex development involves initial imbrication of the Carboniferous section using the BCT as a basal decollement, followed by formation of deeper thrusts in the lower Paleozoic section, which ramp up and merge into the BCT.

  9. The 7-8 August 2008 eruption of Kasatochi Volcano, central Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Waythomas, Christopher F.; Scott, William E.; Prejean, Stephanie G.; Schneider, David J.; Izbekov, Pavel; Nye, Christopher J.

    2010-12-01

    Kasatochi volcano in the central Aleutian Islands erupted unexpectedly on 7-8 August 2008. Kasatochi has received little study by volcanologists and has had no confirmed historical eruptions. The island is an important nesting area for seabirds and a long-term biological study site of the U.S. Fish and Wildlife Service. After a notably energetic preeruptive earthquake swarm, the volcano erupted violently in a series of explosive events beginning in the early afternoon of 7 August. Each event produced ash-gas plumes that reached 14-18 km above sea level. The volcanic plume contained large amounts of SO2 and was tracked around the globe by satellite observations. The cumulative volcanic cloud interfered with air travel across the North Pacific, causing many flight cancelations that affected thousands of travelers. Visits to the volcano in 2008-2009 indicated that the eruption generated pyroclastic flows and surges that swept all flanks of the island, accumulated several tens of meters of pyroclastic debris, and increased the diameter of the island by about 800 m. Pyroclastic flow deposits contain abundant accidental lithic debris derived from the inner walls of the Kasatochi crater. Juvenile material is crystal-rich silicic andesite that ranges from slightly pumiceous to frothy pumice. Fine-grained pyroclastic surge and fall deposits with accretionary lapilli cover the lithic-rich pyroclastic flow deposits and mark a change in eruptive style from episodic explosive activity to more continuous ash emission with smaller intermittent explosions. Pyroclastic deposits completely cover the island, but wave erosion and gully development on the flanks have begun to modify the surface mantle of volcanic deposits.

  10. Multiethnicity, pluralism, and migration in the south central Andes: An alternate path to state expansion.

    PubMed

    Goldstein, Paul S

    2015-07-28

    The south central Andes is known as a region of enduring multiethnic diversity, yet it is also the cradle of one the South America's first successful expansive-state societies. Social structures that encouraged the maintenance of separate identities among coexistent ethnic groups may explain this apparent contradiction. Although the early expansion of the Tiwanaku state (A.D. 600-1000) is often interpreted according to a centralized model derived from Old World precedents, recent archaeological research suggests a reappraisal of the socio-political organization of Tiwanaku civilization, both for the diversity of social entities within its core region and for the multiple agencies behind its wider program of agropastoral colonization. Tiwanaku's sociopolitical pluralism in both its homeland and colonies tempers some of archaeology's global assumptions about the predominant role of centralized institutions in archaic states. PMID:26195732